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Title: Super-Isolated Elliptic Curves and Abelian Surfaces in Cryptography,
Abstract: We call a simple abelian variety over $\mathbb{F}_p$ super-isolated if its
($\mathbb{F}_p$-rational) isogeny class contains no other varieties. The
motivation for considering these varieties comes from concerns about isogeny
based attacks on the discrete log problem. We heuristically estimate that the
number of super-isolated elliptic curves over $\mathbb{F}_p$ with prime order
and $p \leq N$, is roughly $\tilde{\Theta}(\sqrt{N})$. In contrast, we prove
that there are only 2 super-isolated surfaces of cryptographic size and
near-prime order. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Long Short-Term Memory (LSTM) networks with jet constituents for boosted top tagging at the LHC,
Abstract: Multivariate techniques based on engineered features have found wide adoption
in the identification of jets resulting from hadronic top decays at the Large
Hadron Collider (LHC). Recent Deep Learning developments in this area include
the treatment of the calorimeter activation as an image or supplying a list of
jet constituent momenta to a fully connected network. This latter approach
lends itself well to the use of Recurrent Neural Networks. In this work the
applicability of architectures incorporating Long Short-Term Memory (LSTM)
networks is explored. Several network architectures, methods of ordering of jet
constituents, and input pre-processing are studied. The best performing LSTM
network achieves a background rejection of 100 for 50% signal efficiency. This
represents more than a factor of two improvement over a fully connected Deep
Neural Network (DNN) trained on similar types of inputs. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: On Hoffman's conjectural identity,
Abstract: In this paper, we shall prove the equality \[
\zeta(3,\{2\}^{n},1,2)=\zeta(\{2\}^{n+3})+2\zeta(3,3,\{2\}^{n}) \] conjectured
by Hoffman using certain identities among iterated integrals on
$\mathbb{P}^{1}\setminus\{0,1,\infty,z\}$. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Estimate Sequences for Stochastic Composite Optimization: Variance Reduction, Acceleration, and Robustness to Noise,
Abstract: In this paper, we propose a unified view of gradient-based algorithms for
stochastic convex composite optimization. By extending the concept of estimate
sequence introduced by Nesterov, we interpret a large class of stochastic
optimization methods as procedures that iteratively minimize a surrogate of the
objective. This point of view covers stochastic gradient descent (SGD), the
variance-reduction approaches SAGA, SVRG, MISO, their proximal variants, and
has several advantages: (i) we provide a simple generic proof of convergence
for all of the aforementioned methods; (ii) we naturally obtain new algorithms
with the same guarantees; (iii) we derive generic strategies to make these
algorithms robust to stochastic noise, which is useful when data is corrupted
by small random perturbations. Finally, we show that this viewpoint is useful
to obtain accelerated algorithms. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Passive Compliance Control of Aerial Manipulators,
Abstract: This paper presents a passive compliance control for aerial manipulators to
achieve stable environmental interactions. The main challenge is the absence of
actuation along body-planar directions of the aerial vehicle which might be
required during the interaction to preserve passivity. The controller proposed
in this paper guarantees passivity of the manipulator through a proper choice
of end-effector coordinates, and that of vehicle fuselage is guaranteed by
exploiting time domain passivity technique. Simulation studies validate the
proposed approach. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: The phase retrieval problem for solutions of the Helmholtz equation,
Abstract: In this paper we consider the phase retrieval problem for Herglotz functions,
that is, solutions of the Helmholtz equation $\Delta u+\lambda^2u=0$ on domains
$\Omega\subset\mathbb{R}^d$, $d\geq2$. In dimension $d=2$, if $u,v$ are two
such solutions then $|u|=|v|$ implies that either $u=cv$ or $u=c\bar v$ for
some $c\in\mathbb{C}$ with $|c|=1$. In dimension $d\geq3$, the same conclusion
holds under some restriction on $u$ and $v$: either they are real valued or
zonal functions or have non vanishing mean. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Knowledge Discovery from Layered Neural Networks based on Non-negative Task Decomposition,
Abstract: Interpretability has become an important issue in the machine learning field,
along with the success of layered neural networks in various practical tasks.
Since a trained layered neural network consists of a complex nonlinear
relationship between large number of parameters, we failed to understand how
they could achieve input-output mappings with a given data set. In this paper,
we propose the non-negative task decomposition method, which applies
non-negative matrix factorization to a trained layered neural network. This
enables us to decompose the inference mechanism of a trained layered neural
network into multiple principal tasks of input-output mapping, and reveal the
roles of hidden units in terms of their contribution to each principal task. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Deconfined quantum critical points: symmetries and dualities,
Abstract: The deconfined quantum critical point (QCP), separating the Néel and
valence bond solid phases in a 2D antiferromagnet, was proposed as an example
of $2+1$D criticality fundamentally different from standard
Landau-Ginzburg-Wilson-Fisher {criticality}. In this work we present multiple
equivalent descriptions of deconfined QCPs, and use these to address the
possibility of enlarged emergent symmetries in the low energy limit. The
easy-plane deconfined QCP, besides its previously discussed self-duality, is
dual to $N_f = 2$ fermionic quantum electrodynamics (QED), which has its own
self-duality and hence may have an O(4)$\times Z_2^T$ symmetry. We propose
several dualities for the deconfined QCP with ${\mathrm{SU}(2)}$ spin symmetry
which together make natural the emergence of a previously suggested $SO(5)$
symmetry rotating the Néel and VBS orders. These emergent symmetries are
implemented anomalously. The associated infra-red theories can also be viewed
as surface descriptions of 3+1D topological paramagnets, giving further insight
into the dualities. We describe a number of numerical tests of these dualities.
We also discuss the possibility of "pseudocritical" behavior for deconfined
critical points, and the meaning of the dualities and emergent symmetries in
such a scenario. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Link Before You Share: Managing Privacy Policies through Blockchain,
Abstract: With the advent of numerous online content providers, utilities and
applications, each with their own specific version of privacy policies and its
associated overhead, it is becoming increasingly difficult for concerned users
to manage and track the confidential information that they share with the
providers. Users consent to providers to gather and share their Personally
Identifiable Information (PII). We have developed a novel framework to
automatically track details about how a users' PII data is stored, used and
shared by the provider. We have integrated our Data Privacy ontology with the
properties of blockchain, to develop an automated access control and audit
mechanism that enforces users' data privacy policies when sharing their data
across third parties. We have also validated this framework by implementing a
working system LinkShare. In this paper, we describe our framework on detail
along with the LinkShare system. Our approach can be adopted by Big Data users
to automatically apply their privacy policy on data operations and track the
flow of that data across various stakeholders. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Finance"
] |
Title: Convergence Results for Neural Networks via Electrodynamics,
Abstract: We study whether a depth two neural network can learn another depth two
network using gradient descent. Assuming a linear output node, we show that the
question of whether gradient descent converges to the target function is
equivalent to the following question in electrodynamics: Given $k$ fixed
protons in $\mathbb{R}^d,$ and $k$ electrons, each moving due to the attractive
force from the protons and repulsive force from the remaining electrons,
whether at equilibrium all the electrons will be matched up with the protons,
up to a permutation. Under the standard electrical force, this follows from the
classic Earnshaw's theorem. In our setting, the force is determined by the
activation function and the input distribution. Building on this equivalence,
we prove the existence of an activation function such that gradient descent
learns at least one of the hidden nodes in the target network. Iterating, we
show that gradient descent can be used to learn the entire network one node at
a time. | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics",
"Physics"
] |
Title: Nonparametric relative error estimation of the regression function for censored data,
Abstract: Let $ (T_i)_i$ be a sequence of independent identically distributed (i.i.d.)
random variables (r.v.) of interest distributed as $ T$ and $(X_i)_i$ be a
corresponding vector of covariates taking values on $ \mathbb{R}^d$. In
censorship models the r.v. $T$ is subject to random censoring by another r.v.
$C$. In this paper we built a new kernel estimator based on the so-called
synthetic data of the mean squared relative error for the regression function.
We establish the uniform almost sure convergence with rate over a compact set
and its asymptotic normality. The asymptotic variance is explicitly given and
as product we give a confidence bands. A simulation study has been conducted to
comfort our theoretical results | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Towards Probabilistic Formal Modeling of Robotic Cell Injection Systems,
Abstract: Cell injection is a technique in the domain of biological cell
micro-manipulation for the delivery of small volumes of samples into the
suspended or adherent cells. It has been widely applied in various areas, such
as gene injection, in-vitro fertilization (IVF), intracytoplasmic sperm
injection (ISCI) and drug development. However, the existing manual and
semi-automated cell injection systems require lengthy training and suffer from
high probability of contamination and low success rate. In the recently
introduced fully automated cell injection systems, the injection force plays a
vital role in the success of the process since even a tiny excessive force can
destroy the membrane or tissue of the biological cell. Traditionally, the force
control algorithms are analyzed using simulation, which is inherently
non-exhaustive and incomplete in terms of detecting system failures. Moreover,
the uncertainties in the system are generally ignored in the analysis. To
overcome these limitations, we present a formal analysis methodology based on
probabilistic model checking to analyze a robotic cell injection system
utilizing the impedance force control algorithm. The proposed methodology,
developed using the PRISM model checker, allowed to find a discrepancy in the
algorithm, which was not found by any of the previous analysis using the
traditional methods. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Microservices: Granularity vs. Performance,
Abstract: Microservice Architectures (MA) have the potential to increase the agility of
software development. In an era where businesses require software applications
to evolve to support software emerging requirements, particularly for Internet
of Things (IoT) applications, we examine the issue of microservice granularity
and explore its effect upon application latency. Two approaches to microservice
deployment are simulated; the first with microservices in a single container,
and the second with microservices partitioned across separate containers. We
observed a neglibible increase in service latency for the multiple container
deployment over a single container. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Synthesis of Highly Anisotropic Semiconducting GaTe Nanomaterials and Emerging Properties Enabled by Epitaxy,
Abstract: Pseudo-one dimensional (pseudo-1D) materials are a new-class of materials
where atoms are arranged in chain like structures in two-dimensions (2D).
Examples include recently discovered black phosphorus, ReS2 and ReSe2 from
transition metal dichalcogenides, TiS3 and ZrS3 from transition metal
trichalcogenides and most recently GaTe. The presence of structural anisotropy
impacts their physical properties and leads to direction dependent light-matter
interactions, dichroic optical responses, high mobility channels, and
anisotropic thermal conduction. Despite the numerous reports on the vapor phase
growth of isotropic TMDCs and post transition metal chalcogenides such as MoS2
and GaSe, the synthesis of pseudo-1D materials is particularly difficult due to
the anisotropy in interfacial energy, which stabilizes dendritic growth rather
than single crystalline growth with well-defined orientation. The growth of
monoclinic GaTe has been demonstrated on flexible mica substrates with superior
photodetecting performance. In this work, we demonstrate that pseudo-1D
monoclinic GaTe layers can be synthesized on a variety of other substrates
including GaAs (111), Si (111) and c-cut sapphire by physical vapor transport
techniques. High resolution transmission electron microscopy (HRTEM)
measurements, together with angle resolved micro-PL and micro-Raman techniques,
provide for the very first time atomic scale resolution experiments on
pseudo-1D structures in monoclinic GaTe and anisotropic properties.
Interestingly, GaTe nanomaterials grown on sapphire exhibit highly efficient
and narrow localized emission peaks below the band gap energy, which are found
to be related to select types of line and point defects as evidenced by PL and
Raman mapping scans. It makes the samples grown on sapphire more prominent than
those grown on GaAs and Si, which demonstrate more regular properties. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Projection Free Rank-Drop Steps,
Abstract: The Frank-Wolfe (FW) algorithm has been widely used in solving nuclear norm
constrained problems, since it does not require projections. However, FW often
yields high rank intermediate iterates, which can be very expensive in time and
space costs for large problems. To address this issue, we propose a rank-drop
method for nuclear norm constrained problems. The goal is to generate descent
steps that lead to rank decreases, maintaining low-rank solutions throughout
the algorithm. Moreover, the optimization problems are constrained to ensure
that the rank-drop step is also feasible and can be readily incorporated into a
projection-free minimization method, e.g., Frank-Wolfe. We demonstrate that by
incorporating rank-drop steps into the Frank-Wolfe algorithm, the rank of the
solution is greatly reduced compared to the original Frank-Wolfe or its common
variants. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Doubly autoparallel structure on the probability simplex,
Abstract: On the probability simplex, we can consider the standard information
geometric structure with the e- and m-affine connections mutually dual with
respect to the Fisher metric. The geometry naturally defines submanifolds
simultaneously autoparallel for the both affine connections, which we call {\em
doubly autoparallel submanifolds}.
In this note we discuss their several interesting common properties. Further,
we algebraically characterize doubly autoparallel submanifolds on the
probability simplex and give their classification. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Maximum a Posteriori Joint State Path and Parameter Estimation in Stochastic Differential Equations,
Abstract: A wide variety of phenomena of engineering and scientific interest are of a
continuous-time nature and can be modeled by stochastic differential equations
(SDEs), which represent the evolution of the uncertainty in the states of a
system. For systems of this class, some parameters of the SDE might be unknown
and the measured data often includes noise, so state and parameter estimators
are needed to perform inference and further analysis using the system state
path. The distributions of SDEs which are nonlinear or subject to non-Gaussian
measurement noise do not admit tractable analytic expressions, so state and
parameter estimators for these systems are often approximations based on
heuristics, such as the extended and unscented Kalman smoothers, or the
prediction error method using nonlinear Kalman filters. However, the Onsager
Machlup functional can be used to obtain fictitious densities for the
parameters and state-paths of SDEs with analytic expressions. In this thesis,
we provide a unified theoretical framework for maximum a posteriori (MAP)
estimation of general random variables, possibly infinite-dimensional, and show
how the Onsager--Machlup functional can be used to construct the joint MAP
state-path and parameter estimator for SDEs. We also prove that the minimum
energy estimator, which is often thought to be the MAP state-path estimator,
actually gives the state paths associated to the MAP noise paths. Furthermore,
we prove that the discretized MAP state-path and parameter estimators, which
have emerged recently as powerful alternatives to nonlinear Kalman smoothers,
converge hypographically as the discretization step vanishes. Their
hypographical limit, however, is the MAP estimator for SDEs when the
trapezoidal discretization is used and the minimum energy estimator when the
Euler discretization is used, associating different interpretations to each
discretized estimate. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Spreading of an infectious disease between different locations,
Abstract: The endogenous adaptation of agents, that may adjust their local contact
network in response to the risk of being infected, can have the perverse effect
of increasing the overall systemic infectiveness of a disease. We study a
dynamical model over two geographically distinct but interacting locations, to
better understand theoretically the mechanism at play. Moreover, we provide
empirical motivation from the Italian National Bovine Database, for the period
2006-2013. | [
0,
0,
0,
0,
0,
1
] | [
"Quantitative Biology",
"Statistics"
] |
Title: Iterative Machine Teaching,
Abstract: In this paper, we consider the problem of machine teaching, the inverse
problem of machine learning. Different from traditional machine teaching which
views the learners as batch algorithms, we study a new paradigm where the
learner uses an iterative algorithm and a teacher can feed examples
sequentially and intelligently based on the current performance of the learner.
We show that the teaching complexity in the iterative case is very different
from that in the batch case. Instead of constructing a minimal training set for
learners, our iterative machine teaching focuses on achieving fast convergence
in the learner model. Depending on the level of information the teacher has
from the learner model, we design teaching algorithms which can provably reduce
the number of teaching examples and achieve faster convergence than learning
without teachers. We also validate our theoretical findings with extensive
experiments on different data distribution and real image datasets. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Optimization by gradient boosting,
Abstract: Gradient boosting is a state-of-the-art prediction technique that
sequentially produces a model in the form of linear combinations of simple
predictors---typically decision trees---by solving an infinite-dimensional
convex optimization problem. We provide in the present paper a thorough
analysis of two widespread versions of gradient boosting, and introduce a
general framework for studying these algorithms from the point of view of
functional optimization. We prove their convergence as the number of iterations
tends to infinity and highlight the importance of having a strongly convex risk
functional to minimize. We also present a reasonable statistical context
ensuring consistency properties of the boosting predictors as the sample size
grows. In our approach, the optimization procedures are run forever (that is,
without resorting to an early stopping strategy), and statistical
regularization is basically achieved via an appropriate $L^2$ penalization of
the loss and strong convexity arguments. | [
1,
0,
1,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Mathematics"
] |
Title: From Curves to Tropical Jacobians and Back,
Abstract: Given a curve defined over an algebraically closed field which is complete
with respect to a nontrivial valuation, we study its tropical Jacobian. This is
done by first tropicalizing the curve, and then computing the Jacobian of the
resulting weighted metric graph. In general, it is not known how to find the
abstract tropicalization of a curve defined by polynomial equations, since an
embedded tropicalization may not be faithful, and there is no known algorithm
for carrying out semistable reduction in practice. We solve this problem in the
case of hyperelliptic curves by studying admissible covers. We also describe
how to take a weighted metric graph and compute its period matrix, which gives
its tropical Jacobian and tropical theta divisor. Lastly, we describe the
present status of reversing this process, namely how to compute a curve which
has a given matrix as its period matrix. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Asymptotics and Optimal Bandwidth Selection for Nonparametric Estimation of Density Level Sets,
Abstract: Bandwidth selection is crucial in the kernel estimation of density level
sets. Risk based on the symmetric difference between the estimated and true
level sets is usually used to measure their proximity. In this paper we provide
an asymptotic $L^p$ approximation to this risk, where $p$ is characterized by
the weight function in the risk. In particular the excess risk corresponds to
an $L^2$ type of risk, and is adopted in an optimal bandwidth selection rule
for nonparametric level set estimation of $d$-dimensional density functions
($d\geq 1$). | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: A Graph Analytics Framework for Ranking Authors, Papers and Venues,
Abstract: A lot of scientific works are published in different areas of science,
technology, engineering and mathematics. It is not easy, even for experts, to
judge the quality of authors, papers and venues (conferences and journals). An
objective measure to assign scores to these entities and to rank them is very
useful. Although, several metrics and indexes have been proposed earlier, they
suffer from various problems. In this paper, we propose a graph-based analytics
framework to assign scores and to rank authors, papers and venues. Our
algorithm considers only the link structures of the underlying graphs. It does
not take into account other aspects, such as the associated texts and the
reputation of these entities. In the limit of large number of iterations, the
solution of the iterative equations gives the unique entity scores. This
framework can be easily extended to other interdependent networks. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Gradient Sensing via Cell Communication,
Abstract: The chemotactic dynamics of cells and organisms that have no specialized
gradient sensing organelles is not well understood. In fact, chemotaxis of this
sort of organism is especially challenging to explain when the external
chemical gradient is so small as to make variations of concentrations minute
over the length of each of the organisms. Experimental evidence lends support
to the conjecture that chemotactic behavior of chains of cells can be achieved
via cell-to-cell communication. This is the chemotactic basis for the Local
Excitation, Global Inhibition (LEGI) model.
A generalization of the model for the communication component of the LEGI
model is proposed. Doing so permits us to study in detail how gradient sensing
changes as a function of the structure of the communication term. The key
findings of this study are, an accounting of how gradient sensing is affected
by the competition of communication and diffusive processes; the determination
of the scale dependence of the model outcomes; the sensitivity of communication
to parameters in the model. Together with an essential analysis of the dynamics
of the model, these findings can prove useful in suggesting experiments aimed
at determining the viability of a communication mechanism in chemotactic
dynamics of chains and networks of cells exposed to a chemical concentration
gradient. | [
0,
0,
0,
0,
1,
0
] | [
"Quantitative Biology"
] |
Title: Nichols Algebras and Quantum Principal Bundles,
Abstract: A general procedure for constructing Yetter-Drinfeld modules from quantum
principal bundles is introduced. As an application a Yetter-Drinfeld structure
is put on the cotangent space of the Heckenberger-Kolb calculi of the quantum
Grassmannians. For the special case of quantum projective space the associated
braiding is shown to be non-diagonal and of Hecke type. Moreover, its Nichols
algebra is shown to be finite-dimensional and equal to the anti-holomorphic
part of the total differential calculus. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Inference of signals with unknown correlation structure from nonlinear measurements,
Abstract: We present a method to reconstruct autocorrelated signals together with their
autocorrelation structure from nonlinear, noisy measurements for arbitrary
monotonous nonlinear instrument response. In the presented formulation the
algorithm provides a significant speedup compared to prior implementations,
allowing for a wider range of application. The nonlinearity can be used to
model instrument characteristics or to enforce properties on the underlying
signal, such as positivity. Uncertainties on any posterior quantities can be
provided due to independent samples from an approximate posterior distribution.
We demonstrate the methods applicability via simulated and real measurements,
using different measurement instruments, nonlinearities and dimensionality. | [
0,
1,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Optical and structural study of the pressure-induced phase transition of CdWO$_4$,
Abstract: The optical absorption of CdWO$_4$ is reported at high pressures up to 23
GPa. The onset of a phase transition was detected at 19.5 GPa, in good
agreement with a previous Raman spectroscopy study. The crystal structure of
the high-pressure phase of CdWO$_4$ was solved at 22 GPa employing
single-crystal synchrotron x-ray diffraction. The symmetry changes from space
group $P$2/$c$ in the low-pressure wolframite phase to $P2_1/c$ in the
high-pressure post-wolframite phase accompanied by a doubling of the unit-cell
volume. The octahedral oxygen coordination of the tungsten and cadmium ions is
increased to [7]-fold and [6+1]-fold, respectively, at the phase transition.
The compressibility of the low-pressure phase of CdWO$_4$ has been reevaluated
with powder x-ray diffraction up to 15 GPa finding a bulk modulus of $B_0$ =
123 GPa. The direct band gap of the low-pressure phase increases with
compression up to 16.9 GPa at 12 meV/GPa. At this point an indirect band gap
crosses the direct band gap and decreases at -2 meV/GPa up to 19.5 GPa where
the phase transition starts. At the phase transition the band gap collapses by
0.7 eV and another direct band gap decreases at -50 meV/GPa up to the maximum
measured pressure. The structural stability of the post-wolframite structure is
confirmed by \textit{ab initio} calculations finding the post-wolframite-type
phase to be more stable than the wolframite at 18 GPa. Lattice dynamic
calculations based on space group $P2_1/c$ explain well the Raman-active modes
previously measured in the high-pressure post-wolframite phase. The
pressure-induced band gap crossing in the wolframite phase as well as the
pressure dependence of the direct band gap in the high-pressure phase are
further discussed with respect to the calculations. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Learning Context-Sensitive Convolutional Filters for Text Processing,
Abstract: Convolutional neural networks (CNNs) have recently emerged as a popular
building block for natural language processing (NLP). Despite their success,
most existing CNN models employed in NLP share the same learned (and static)
set of filters for all input sentences. In this paper, we consider an approach
of using a small meta network to learn context-sensitive convolutional filters
for text processing. The role of meta network is to abstract the contextual
information of a sentence or document into a set of input-aware filters. We
further generalize this framework to model sentence pairs, where a
bidirectional filter generation mechanism is introduced to encapsulate
co-dependent sentence representations. In our benchmarks on four different
tasks, including ontology classification, sentiment analysis, answer sentence
selection, and paraphrase identification, our proposed model, a modified CNN
with context-sensitive filters, consistently outperforms the standard CNN and
attention-based CNN baselines. By visualizing the learned context-sensitive
filters, we further validate and rationalize the effectiveness of proposed
framework. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Approximate Ranking from Pairwise Comparisons,
Abstract: A common problem in machine learning is to rank a set of n items based on
pairwise comparisons. Here ranking refers to partitioning the items into sets
of pre-specified sizes according to their scores, which includes identification
of the top-k items as the most prominent special case. The score of a given
item is defined as the probability that it beats a randomly chosen other item.
Finding an exact ranking typically requires a prohibitively large number of
comparisons, but in practice, approximate rankings are often adequate.
Accordingly, we study the problem of finding approximate rankings from pairwise
comparisons. We analyze an active ranking algorithm that counts the number of
comparisons won, and decides whether to stop or which pair of items to compare
next, based on confidence intervals computed from the data collected in
previous steps. We show that this algorithm succeeds in recovering approximate
rankings using a number of comparisons that is close to optimal up to
logarithmic factors. We also present numerical results, showing that in
practice, approximation can drastically reduce the number of comparisons
required to estimate a ranking. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: On Recoverable and Two-Stage Robust Selection Problems with Budgeted Uncertainty,
Abstract: In this paper the problem of selecting $p$ out of $n$ available items is
discussed, such that their total cost is minimized. We assume that costs are
not known exactly, but stem from a set of possible outcomes.
Robust recoverable and two-stage models of this selection problem are
analyzed. In the two-stage problem, up to $p$ items is chosen in the first
stage, and the solution is completed once the scenario becomes revealed in the
second stage. In the recoverable problem, a set of $p$ items is selected in the
first stage, and can be modified by exchanging up to $k$ items in the second
stage, after a scenario reveals.
We assume that uncertain costs are modeled through bounded uncertainty sets,
i.e., the interval uncertainty sets with an additional linear (budget)
constraint, in their discrete and continuous variants. Polynomial algorithms
for recoverable and two-stage selection problems with continuous bounded
uncertainty, and compact mixed integer formulations in the case of discrete
bounded uncertainty are constructed. | [
1,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Computer Science"
] |
Title: The homotopy Lie algebra of symplectomorphism groups of 3-fold blow-ups of $(S^2 \times S^2, σ_{std} \oplus σ_{std}) $,
Abstract: We consider the 3-point blow-up of the manifold $ (S^2 \times S^2, \sigma
\oplus \sigma)$ where $\sigma$ is the standard symplectic form which gives area
1 to the sphere $S^2$, and study its group of symplectomorphisms $\rm{Symp} (
S^2 \times S^2 \#\, 3\overline{\mathbb C\mathbb P}\,\!^2, \omega)$. So far, the
monotone case was studied by J. Evans and he proved that this group is
contractible. Moreover, J. Li, T. J. Li and W. Wu showed that the group
Symp$_{h}(S^2 \times S^2 \#\, 3\overline{ \mathbb C\mathbb P}\,\!^2,\omega) $
of symplectomorphisms that act trivially on homology is always connected and
recently they also computed its fundamental group. We describe, in full detail,
the rational homotopy Lie algebra of this group.
We show that some particular circle actions contained in the
symplectomorphism group generate its full topology. More precisely, they give
the generators of the homotopy graded Lie algebra of $\rm{Symp} (S^2 \times S^2
\#\, 3\overline{ \mathbb C\mathbb P}\,\!^2, \omega)$. Our study depends on
Karshon's classification of Hamiltonian circle actions and the inflation
technique introduced by Lalonde-McDuff. As an application, we deduce the rank
of the homotopy groups of $\rm{Symp}({\mathbb C\mathbb P}^2 \#\,
5\overline{\mathbb C\mathbb P}\,\!^2, \tilde \omega)$, in the case of small
blow-ups. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Linguistic Matrix Theory,
Abstract: Recent research in computational linguistics has developed algorithms which
associate matrices with adjectives and verbs, based on the distribution of
words in a corpus of text. These matrices are linear operators on a vector
space of context words. They are used to construct the meaning of composite
expressions from that of the elementary constituents, forming part of a
compositional distributional approach to semantics. We propose a Matrix Theory
approach to this data, based on permutation symmetry along with Gaussian
weights and their perturbations. A simple Gaussian model is tested against word
matrices created from a large corpus of text. We characterize the cubic and
quartic departures from the model, which we propose, alongside the Gaussian
parameters, as signatures for comparison of linguistic corpora. We propose that
perturbed Gaussian models with permutation symmetry provide a promising
framework for characterizing the nature of universality in the statistical
properties of word matrices. The matrix theory framework developed here
exploits the view of statistics as zero dimensional perturbative quantum field
theory. It perceives language as a physical system realizing a universality
class of matrix statistics characterized by permutation symmetry. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Fast Spectral Clustering Using Autoencoders and Landmarks,
Abstract: In this paper, we introduce an algorithm for performing spectral clustering
efficiently. Spectral clustering is a powerful clustering algorithm that
suffers from high computational complexity, due to eigen decomposition. In this
work, we first build the adjacency matrix of the corresponding graph of the
dataset. To build this matrix, we only consider a limited number of points,
called landmarks, and compute the similarity of all data points with the
landmarks. Then, we present a definition of the Laplacian matrix of the graph
that enable us to perform eigen decomposition efficiently, using a deep
autoencoder. The overall complexity of the algorithm for eigen decomposition is
$O(np)$, where $n$ is the number of data points and $p$ is the number of
landmarks. At last, we evaluate the performance of the algorithm in different
experiments. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Gate-controlled magnonic-assisted switching of magnetization in ferroelectric/ferromagnetic junctions,
Abstract: Interfacing a ferromagnet with a polarized ferroelectric gate generates a
non-uniform, interfacial spin density coupled to the ferroelectric polarization
allowing so for an electric field control of effective transversal field to
magnetization. Here we study the dynamic magnetization switching behavior of
such a multilayer system based on the Landau-Lifshitz-Baryakhtar equation,
demonstrating that interfacial magnetoelectric coupling is utilizable as a
highly localized and efficient tool for manipulating magnetism. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: MUTAN: Multimodal Tucker Fusion for Visual Question Answering,
Abstract: Bilinear models provide an appealing framework for mixing and merging
information in Visual Question Answering (VQA) tasks. They help to learn high
level associations between question meaning and visual concepts in the image,
but they suffer from huge dimensionality issues. We introduce MUTAN, a
multimodal tensor-based Tucker decomposition to efficiently parametrize
bilinear interactions between visual and textual representations. Additionally
to the Tucker framework, we design a low-rank matrix-based decomposition to
explicitly constrain the interaction rank. With MUTAN, we control the
complexity of the merging scheme while keeping nice interpretable fusion
relations. We show how our MUTAN model generalizes some of the latest VQA
architectures, providing state-of-the-art results. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Viscosity solutions and the minimal surface system,
Abstract: We give a definition of viscosity solution for the minimal surface system and
prove a version of Allard regularity theorem in this setting. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Ray-tracing semiclassical low frequency acoustic modeling with local and extended reaction boundaries,
Abstract: The recently introduced acoustic ray-tracing semiclassical (RTS) method is
validated for a set of practically relevant boundary conditions. RTS is a
frequency domain geometrical method which directly reproduces the acoustic
Green's function. As previously demonstrated for a rectangular room and weakly
absorbing boundaries with a real and frequency-independent impedance, RTS is
capable of modeling also the lowest modes of such a room, which makes it a
useful method for low frequency sound field modeling in enclosures. In
practice, rooms are furnished with diverse types of materials and acoustic
elements, resulting in a frequency-dependent, phase-modifying
absorption/reflection. In a realistic setting, we test the RTS method with two
additional boundary conditions: a local reaction boundary simulating a
resonating membrane absorber and an extended reaction boundary representing a
porous layer backed by a rigid boundary described within the Delany-Bazley-Miki
model, as well as a combination thereof. The RTS-modeled spatially dependent
pressure response and octave band decay curves with the corresponding
reverberation times are compared to those obtained by the finite element
method. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Hierarchical State Abstractions for Decision-Making Problems with Computational Constraints,
Abstract: In this semi-tutorial paper, we first review the information-theoretic
approach to account for the computational costs incurred during the search for
optimal actions in a sequential decision-making problem. The traditional (MDP)
framework ignores computational limitations while searching for optimal
policies, essentially assuming that the acting agent is perfectly rational and
aims for exact optimality. Using the free-energy, a variational principle is
introduced that accounts not only for the value of a policy alone, but also
considers the cost of finding this optimal policy. The solution of the
variational equations arising from this formulation can be obtained using
familiar Bellman-like value iterations from dynamic programming (DP) and the
Blahut-Arimoto (BA) algorithm from rate distortion theory. Finally, we
demonstrate the utility of the approach for generating hierarchies of state
abstractions that can be used to best exploit the available computational
resources. A numerical example showcases these concepts for a path-planning
problem in a grid world environment. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: The content correlation of multiple streaming edges,
Abstract: We study how to detect clusters in a graph defined by a stream of edges,
without storing the entire graph. We extend the approach to dynamic graphs
defined by the most recent edges of the stream and to several streams. The {\em
content correlation }of two streams $\rho(t)$ is the Jaccard similarity of
their clusters in the windows before time $t$. We propose a simple and
efficient method to approximate this correlation online and show that for
dynamic random graphs which follow a power law degree distribution, we can
guarantee a good approximation. As an application, we follow Twitter streams
and compute their content correlations online. We then propose a {\em search by
correlation} where answers to sets of keywords are entirely based on the small
correlations of the streams. Answers are ordered by the correlations, and
explanations can be traced with the stored clusters. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Precision Prediction for the Cosmological Density Distribution,
Abstract: The distribution of matter in the universe is, to first order, lognormal.
Improving this approximation requires characterization of the third moment
(skewness) of the log density field. Thus, using Millennium Simulation
phenomenology and building on previous work, we present analytic fits for the
mean, variance, and skewness of the log density field $A$. We further show that
a Generalized Extreme Value (GEV) distribution accurately models $A$; we submit
that this GEV behavior is the result of strong intrapixel correlations, without
which the smoothed distribution would tend (by the Central Limit Theorem)
toward a Gaussian. Our GEV model yields cumulative distribution functions
accurate to within 1.7 per cent for near-concordance cosmologies, over a range
of redshifts and smoothing scales. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Towards Arbitrary Noise Augmentation - Deep Learning for Sampling from Arbitrary Probability Distributions,
Abstract: Accurate noise modelling is important for training of deep learning
reconstruction algorithms. While noise models are well known for traditional
imaging techniques, the noise distribution of a novel sensor may be difficult
to determine a priori. Therefore, we propose learning arbitrary noise
distributions. To do so, this paper proposes a fully connected neural network
model to map samples from a uniform distribution to samples of any explicitly
known probability density function. During the training, the Jensen-Shannon
divergence between the distribution of the model's output and the target
distribution is minimized. We experimentally demonstrate that our model
converges towards the desired state. It provides an alternative to existing
sampling methods such as inversion sampling, rejection sampling, Gaussian
mixture models and Markov-Chain-Monte-Carlo. Our model has high sampling
efficiency and is easily applied to any probability distribution, without the
need of further analytical or numerical calculations. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Computing the Lusztig--Vogan Bijection,
Abstract: Let $G$ be a connected complex reductive algebraic group with Lie algebra
$\mathfrak{g}$. The Lusztig--Vogan bijection relates two bases for the bounded
derived category of $G$-equivariant coherent sheaves on the nilpotent cone
$\mathcal{N}$ of $\mathfrak{g}$. One basis is indexed by $\Lambda^+$, the set
of dominant weights of $G$, and the other by $\Omega$, the set of pairs
$(\mathcal{O}, \mathcal{E})$ consisting of a nilpotent orbit $\mathcal{O}
\subset \mathcal{N}$ and an irreducible $G$-equivariant vector bundle
$\mathcal{E} \rightarrow \mathcal{O}$. The existence of the Lusztig--Vogan
bijection $\gamma \colon \Omega \rightarrow \Lambda^+$ was proven by
Bezrukavnikov, and an algorithm computing $\gamma$ in type $A$ was given by
Achar. Herein we present a combinatorial description of $\gamma$ in type $A$
that subsumes and dramatically simplifies Achar's algorithm. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Divide and Conquer: Variable Set Separation in Hybrid Systems Reachability Analysis,
Abstract: In this paper we propose an improvement for flowpipe-construction-based
reachability analysis techniques for hybrid systems. Such methods apply
iterative successor computations to pave the reachable region of the state
space by state sets in an over-approximative manner. As the computational costs
steeply increase with the dimension, in this work we analyse the possibilities
for improving scalability by dividing the search space in sub-spaces and
execute reachability computations in the sub-spaces instead of the global
space. We formalise such an algorithm and provide experimental evaluations to
compare the efficiency as well as the precision of our sub-space search to the
original search in the global space. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Hierarchy of Information Scrambling, Thermalization, and Hydrodynamic Flow in Graphene,
Abstract: We determine the information scrambling rate $\lambda_{L}$ due to
electron-electron Coulomb interaction in graphene. $\lambda_{L}$ characterizes
the growth of chaos and has been argued to give information about the
thermalization and hydrodynamic transport coefficients of a many-body system.
We demonstrate that $\lambda_{L}$ behaves for strong coupling similar to
transport and energy relaxation rates. A weak coupling analysis, however,
reveals that scrambling is related to dephasing or single particle relaxation.
Furthermore, $\lambda_{L}$ is found to be parametrically larger than the
collision rate relevant for hydrodynamic processes, such as electrical
conduction or viscous flow, and the rate of energy relaxation, relevant for
thermalization. Thus, while scrambling is obviously necessary for
thermalization and quantum transport, it does generically not set the time
scale for these processes. In addition we derive a quantum kinetic theory for
information scrambling that resembles the celebrated Boltzmann equation and
offers a physically transparent insight into quantum chaos in many-body
systems. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Neural Collaborative Autoencoder,
Abstract: In recent years, deep neural networks have yielded state-of-the-art
performance on several tasks. Although some recent works have focused on
combining deep learning with recommendation, we highlight three issues of
existing models. First, these models cannot work on both explicit and implicit
feedback, since the network structures are specially designed for one
particular case. Second, due to the difficulty on training deep neural
networks, existing explicit models do not fully exploit the expressive
potential of deep learning. Third, neural network models are easier to overfit
on the implicit setting than shallow models. To tackle these issues, we present
a generic recommender framework called Neural Collaborative Autoencoder (NCAE)
to perform collaborative filtering, which works well for both explicit feedback
and implicit feedback. NCAE can effectively capture the subtle hidden
relationships between interactions via a non-linear matrix factorization
process. To optimize the deep architecture of NCAE, we develop a three-stage
pre-training mechanism that combines supervised and unsupervised feature
learning. Moreover, to prevent overfitting on the implicit setting, we propose
an error reweighting module and a sparsity-aware data-augmentation strategy.
Extensive experiments on three real-world datasets demonstrate that NCAE can
significantly advance the state-of-the-art. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Pentavalent symmetric graphs of order four times an odd square-free integer,
Abstract: A graph is said to be symmetric if its automorphism group is transitive on
its arcs. Guo et al. (Electronic J. Combin. 18, \#P233, 2011) and Pan et al.
(Electronic J. Combin. 20, \#P36, 2013) determined all pentavalent symmetric
graphs of order $4pq$. In this paper, we shall generalize this result by
determining all connected pentavalent symmetric graphs of order four times an
odd square-free integer. It is shown in this paper that, for each of such
graphs $\it\Gamma$, either the full automorphism group ${\sf Aut}\it\Gamma$ is
isomorphic to ${\sf PSL}(2,p)$, ${\sf PGL}(2,p)$, ${\sf
PSL}(2,p){\times}\mathbb{Z}_2$ or ${\sf PGL}(2,p){\times}\mathbb{Z}_2$, or
$\it\Gamma$ is isomorphic to one of 8 graphs. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Implementing implicit OpenMP data sharing on GPUs,
Abstract: OpenMP is a shared memory programming model which supports the offloading of
target regions to accelerators such as NVIDIA GPUs. The implementation in
Clang/LLVM aims to deliver a generic GPU compilation toolchain that supports
both the native CUDA C/C++ and the OpenMP device offloading models. There are
situations where the semantics of OpenMP and those of CUDA diverge. One such
example is the policy for implicitly handling local variables. In CUDA, local
variables are implicitly mapped to thread local memory and thus become private
to a CUDA thread. In OpenMP, due to semantics that allow the nesting of regions
executed by different numbers of threads, variables need to be implicitly
\emph{shared} among the threads of a contention group. In this paper we
introduce a re-design of the OpenMP device data sharing infrastructure that is
responsible for the implicit sharing of local variables in the Clang/LLVM
toolchain. We introduce a new data sharing infrastructure that lowers
implicitly shared variables to the shared memory of the GPU. We measure the
amount of shared memory used by our scheme in cases that involve scalar
variables and statically allocated arrays. The evaluation is carried out by
offloading to K40 and P100 NVIDIA GPUs. For scalar variables the pressure on
shared memory is relatively low, under 26\% of shared memory utilization for
the K40, and does not negatively impact occupancy. The limiting occupancy
factor in that case is register pressure. The data sharing scheme offers the
users a simple memory model for controlling the implicit allocation of device
shared memory. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Real-Time Impulse Noise Removal from MR Images for Radiosurgery Applications,
Abstract: In the recent years image processing techniques are used as a tool to improve
detection and diagnostic capabilities in the medical applications. Medical
applications have been so much affected by these techniques which some of them
are embedded in medical instruments such as MRI, CT and other medical devices.
Among these techniques, medical image enhancement algorithms play an essential
role in removal of the noise which can be produced by medical instruments and
during image transfer. It has been proved that impulse noise is a major type of
noise, which is produced during medical operations, such as MRI, CT, and
angiography, by their image capturing devices. An embeddable hardware module
which is able to denoise medical images before and during surgical operations
could be very helpful. In this paper an accurate algorithm is proposed for
real-time removal of impulse noise in medical images. All image blocks are
divided into three categories of edge, smooth, and disordered areas. A
different reconstruction method is applied to each category of blocks for the
purpose of noise removal. The proposed method is tested on MR images.
Simulation results show acceptable denoising accuracy for various levels of
noise. Also an FPAG implementation of our denoising algorithm shows acceptable
hardware resource utilization. Hence, the algorithm is suitable for embedding
in medical hardware instruments such as radiosurgery devices. | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Randomized CP Tensor Decomposition,
Abstract: The CANDECOMP/PARAFAC (CP) tensor decomposition is a popular
dimensionality-reduction method for multiway data. Dimensionality reduction is
often sought since many high-dimensional tensors have low intrinsic rank
relative to the dimension of the ambient measurement space. However, the
emergence of `big data' poses significant computational challenges for
computing this fundamental tensor decomposition. Leveraging modern randomized
algorithms, we demonstrate that the coherent structure can be learned from a
smaller representation of the tensor in a fraction of the time. Moreover, the
high-dimensional signal can be faithfully approximated from the compressed
measurements. Thus, this simple but powerful algorithm enables one to compute
the approximate CP decomposition even for massive tensors. The approximation
error can thereby be controlled via oversampling and the computation of power
iterations. In addition to theoretical results, several empirical results
demonstrate the performance of the proposed algorithm. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Adversarial Attacks on Node Embeddings,
Abstract: The goal of network representation learning is to learn low-dimensional node
embeddings that capture the graph structure and are useful for solving
downstream tasks. However, despite the proliferation of such methods there is
currently no study of their robustness to adversarial attacks. We provide the
first adversarial vulnerability analysis on the widely used family of methods
based on random walks. We derive efficient adversarial perturbations that
poison the network structure and have a negative effect on both the quality of
the embeddings and the downstream tasks. We further show that our attacks are
transferable -- they generalize to many models -- and are successful even when
the attacker has restricted actions. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Dimensionality-strain phase diagram of strontium iridates,
Abstract: The competition between spin-orbit coupling, bandwidth ($W$) and
electron-electron interaction ($U$) makes iridates highly susceptible to small
external perturbations, which can trigger the onset of novel types of
electronic and magnetic states. Here we employ {\em first principles}
calculations based on density functional theory and on the constrained random
phase approximation to study how dimensionality and strain affect the strength
of $U$ and $W$ in (SrIrO$_3$)$_m$/(SrTiO$_3$) superlattices. The result is a
phase diagram explaining two different types of controllable magnetic and
electronic transitions, spin-flop and insulator-to-metal, connected with the
disruption of the $J_{eff}=1/2$ state which cannnot be understood within a
simplified local picture. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: SGDLibrary: A MATLAB library for stochastic gradient descent algorithms,
Abstract: We consider the problem of finding the minimizer of a function $f:
\mathbb{R}^d \rightarrow \mathbb{R}$ of the finite-sum form $\min f(w) =
1/n\sum_{i}^n f_i(w)$. This problem has been studied intensively in recent
years in the field of machine learning (ML). One promising approach for
large-scale data is to use a stochastic optimization algorithm to solve the
problem. SGDLibrary is a readable, flexible and extensible pure-MATLAB library
of a collection of stochastic optimization algorithms. The purpose of the
library is to provide researchers and implementers a comprehensive evaluation
environment for the use of these algorithms on various ML problems. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Optimization, fast and slow: optimally switching between local and Bayesian optimization,
Abstract: We develop the first Bayesian Optimization algorithm, BLOSSOM, which selects
between multiple alternative acquisition functions and traditional local
optimization at each step. This is combined with a novel stopping condition
based on expected regret. This pairing allows us to obtain the best
characteristics of both local and Bayesian optimization, making efficient use
of function evaluations while yielding superior convergence to the global
minimum on a selection of optimization problems, and also halting optimization
once a principled and intuitive stopping condition has been fulfilled. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Optimization of exposure time division for wide field observations,
Abstract: The optical observations of wide fields of view encounter the problem of
selection of best exposure time. As there are usually plenty of objects
observed simultaneously, the quality of photometry of the brightest ones is
always better than of the dimmer ones. Frequently all of them are equally
interesting for the astronomers and thus it is desired to have all of them
measured with the highest possible accuracy.
In this paper we present a novel optimization algorithm dedicated for the
division of exposure time into sub-exposures, which allows to perform
photometry with more balanced noise budget. Thanks to the proposed technique,
the photometric precision of dimmer objects is increased at the expense of the
measurement fidelity of the brightest ones. We tested the method on real
observations using two telescope setups demonstrating its usefulness and good
agreement with the theoretical expectations. The main application of our
approach is a wide range of sky surveys, including the ones performed by the
space telescopes. The method can be applied for planning virtually any
photometric observations, in which the objects of interest show a wide range of
magnitudes. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: DNN-Buddies: A Deep Neural Network-Based Estimation Metric for the Jigsaw Puzzle Problem,
Abstract: This paper introduces the first deep neural network-based estimation metric
for the jigsaw puzzle problem. Given two puzzle piece edges, the neural network
predicts whether or not they should be adjacent in the correct assembly of the
puzzle, using nothing but the pixels of each piece. The proposed metric
exhibits an extremely high precision even though no manual feature extraction
is performed. When incorporated into an existing puzzle solver, the solution's
accuracy increases significantly, achieving thereby a new state-of-the-art
standard. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Attack Analysis for Distributed Control Systems: An Internal Model Principle Approach,
Abstract: Although adverse effects of attacks have been acknowledged in many
cyber-physical systems, there is no system-theoretic comprehension of how a
compromised agent can leverage communication capabilities to maximize the
damage in distributed multi-agent systems. A rigorous analysis of
cyber-physical attacks enables us to increase the system awareness against
attacks and design more resilient control protocols. To this end, we will take
the role of the attacker to identify the worst effects of attacks on root nodes
and non-root nodes in a distributed control system. More specifically, we show
that a stealthy attack on root nodes can mislead the entire network to a wrong
understanding of the situation and even destabilize the synchronization
process. This will be called the internal model principle for the attacker and
will intensify the urgency of designing novel control protocols to mitigate
these types of attacks. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: See the Near Future: A Short-Term Predictive Methodology to Traffic Load in ITS,
Abstract: The Intelligent Transportation System (ITS) targets to a coordinated traffic
system by applying the advanced wireless communication technologies for road
traffic scheduling. Towards an accurate road traffic control, the short-term
traffic forecasting to predict the road traffic at the particular site in a
short period is often useful and important. In existing works, Seasonal
Autoregressive Integrated Moving Average (SARIMA) model is a popular approach.
The scheme however encounters two challenges: 1) the analysis on related data
is insufficient whereas some important features of data may be neglected; and
2) with data presenting different features, it is unlikely to have one
predictive model that can fit all situations. To tackle above issues, in this
work, we develop a hybrid model to improve accuracy of SARIMA. In specific, we
first explore the autocorrelation and distribution features existed in traffic
flow to revise structure of the time series model. Based on the Gaussian
distribution of traffic flow, a hybrid model with a Bayesian learning algorithm
is developed which can effectively expand the application scenarios of SARIMA.
We show the efficiency and accuracy of our proposal using both analysis and
experimental studies. Using the real-world trace data, we show that the
proposed predicting approach can achieve satisfactory performance in practice. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Single-Crystal N-polar GaN p-n Diodes by Plasma-Assisted Molecular Beam Epitaxy,
Abstract: N-polar GaN p-n diodes are realized on single-crystal N-polar GaN bulk wafers
by plasma-assisted molecular beam epitaxy growth. The current-voltage
characteristics show high-quality rectification and electroluminescence
characteristics with a high on/off current ratio and interband photon emission.
The measured electroluminescence spectrum is dominated by strong near-band edge
emission, while deep level luminescence is greatly suppressed. A very low
dislocation density leads to a high reverse breakdown electric field. The low
leakage current N-polar diodes open up several potential applications in
polarization-engineered photonic and electronic devices. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Long-term Blood Pressure Prediction with Deep Recurrent Neural Networks,
Abstract: Existing methods for arterial blood pressure (BP) estimation directly map the
input physiological signals to output BP values without explicitly modeling the
underlying temporal dependencies in BP dynamics. As a result, these models
suffer from accuracy decay over a long time and thus require frequent
calibration. In this work, we address this issue by formulating BP estimation
as a sequence prediction problem in which both the input and target are
temporal sequences. We propose a novel deep recurrent neural network (RNN)
consisting of multilayered Long Short-Term Memory (LSTM) networks, which are
incorporated with (1) a bidirectional structure to access larger-scale context
information of input sequence, and (2) residual connections to allow gradients
in deep RNN to propagate more effectively. The proposed deep RNN model was
tested on a static BP dataset, and it achieved root mean square error (RMSE) of
3.90 and 2.66 mmHg for systolic BP (SBP) and diastolic BP (DBP) prediction
respectively, surpassing the accuracy of traditional BP prediction models. On a
multi-day BP dataset, the deep RNN achieved RMSE of 3.84, 5.25, 5.80 and 5.81
mmHg for the 1st day, 2nd day, 4th day and 6th month after the 1st day SBP
prediction, and 1.80, 4.78, 5.0, 5.21 mmHg for corresponding DBP prediction,
respectively, which outperforms all previous models with notable improvement.
The experimental results suggest that modeling the temporal dependencies in BP
dynamics significantly improves the long-term BP prediction accuracy. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Fast Rigid 3D Registration Solution: A Simple Method Free of SVD and Eigen-Decomposition,
Abstract: A novel solution is obtained to solve the rigid 3D registration problem,
motivated by previous eigen-decomposition approaches. Different from existing
solvers, the proposed algorithm does not require sophisticated matrix
operations e.g. singular value decomposition or eigenvalue decomposition.
Instead, the optimal eigenvector of the point cross-covariance matrix can be
computed within several iterations. It is also proven that the optimal rotation
matrix can be directly computed for cases without need of quaternion. The
simple framework provides very easy approach of integer-implementation on
embedded platforms. Simulations on noise-corrupted point clouds have verified
the robustness and computation speed of the proposed method. The final results
indicate that the proposed algorithm is accurate, robust and owns over $60\%
\sim 80\%$ less computation time than representatives. It has also been applied
to real-world applications for faster relative robotic navigation. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Scale relativistic formulation of non-differentiable mechanics II: The Schroedinger picture,
Abstract: This article is the second in a series of two presenting the Scale
Relativistic approach to non-differentiability in mechanics and its relation to
quantum mechanics. Here, we show Schroedinger's equation to be a reformulation
of Newton's fundamental relation of dynamics as generalized to
non-differentiable geometries in the first paper \cite{paper1}. It motivates an
alternative interpretation of the other axioms of standard quantum mechanics in
a coherent picture. This exercise validates the Scale Relativistic approach
and, at the same time, it allows to identify macroscopic chaotic systems
considered at time scales exceeding their horizon of predictability as
candidates in which to search for quantum-like structuring or behavior. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Manifold learning with bi-stochastic kernels,
Abstract: In this paper we answer the following question: what is the infinitesimal
generator of the diffusion process defined by a kernel that is normalized such
that it is bi-stochastic with respect to a specified measure? More precisely,
under the assumption that data is sampled from a Riemannian manifold we
determine how the resulting infinitesimal generator depends on the potentially
nonuniform distribution of the sample points, and the specified measure for the
bi-stochastic normalization. In a special case, we demonstrate a connection to
the heat kernel. We consider both the case where only a single data set is
given, and the case where a data set and a reference set are given. The
spectral theory of the constructed operators is studied, and Nyström
extension formulas for the gradients of the eigenfunctions are computed.
Applications to discrete point sets and manifold learning are discussed. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics",
"Computer Science"
] |
Title: A local search 2.917-approximation algorithm for duo-preservation string mapping,
Abstract: We study the {\em maximum duo-preservation string mapping} ({\sc Max-Duo})
problem, which is the complement of the well studied {\em minimum common string
partition} ({\sc MCSP}) problem. Both problems have applications in many fields
including text compression and bioinformatics. Motivated by an earlier local
search algorithm, we present an improved approximation and show that its
performance ratio is no greater than ${35}/{12} < 2.917$. This beats the
current best $3.25$-approximation for {\sc Max-Duo}. The performance analysis
of our algorithm is done through a complex yet interesting amortization. Two
lower bounds on the locality gap of our algorithm are also provided. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Using Graphs of Classifiers to Impose Declarative Constraints on Semi-supervised Learning,
Abstract: We propose a general approach to modeling semi-supervised learning (SSL)
algorithms. Specifically, we present a declarative language for modeling both
traditional supervised classification tasks and many SSL heuristics, including
both well-known heuristics such as co-training and novel domain-specific
heuristics. In addition to representing individual SSL heuristics, we show that
multiple heuristics can be automatically combined using Bayesian optimization
methods. We experiment with two classes of tasks, link-based text
classification and relation extraction. We show modest improvements on
well-studied link-based classification benchmarks, and state-of-the-art results
on relation-extraction tasks for two realistic domains. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Fabrication of a centimeter-long cavity on a nanofiber for cavity QED,
Abstract: We report the fabrication of a 1.2 cm long cavity directly on a nanofiber
using femtosecond laser ablation. The cavity modes with finesse value in the
range 200-400 can still maintain the transmission between 40-60%, which can
enable "strong-coupling" regime of cavity QED for a single atom trapped 200 nm
away from the fiber surface. For such cavity modes, we estimate the one-pass
intra-cavity transmission to be 99.53%. Other cavity modes, which can enable
high cooperativity in the range 3-10, show transmission over 60-85% and are
suitable for fiber-based single photon sources and quantum nonlinear optics in
the "Purcell" regime. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Strongly convex stochastic online optimization on a unit simplex with application to the mixing least square regression,
Abstract: In this paper we propose a new approach to obtain mixing least square
regression estimate by means of stochastic online mirror descent in
non-euclidian set-up. | [
0,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics",
"Statistics"
] |
Title: Unifying DAGs and UGs,
Abstract: We introduce a new class of graphical models that generalizes
Lauritzen-Wermuth-Frydenberg chain graphs by relaxing the semi-directed
acyclity constraint so that only directed cycles are forbidden. Moreover, up to
two edges are allowed between any pair of nodes. Specifically, we present
local, pairwise and global Markov properties for the new graphical models and
prove their equivalence. We also present an equivalent factorization property.
Finally, we present a causal interpretation of the new models. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Program Completionin the Input Language of GRINGO,
Abstract: We argue that turning a logic program into a set of completed definitions can
be sometimes thought of as the "reverse engineering" process of generating a
set of conditions that could serve as a specification for it. Accordingly, it
may be useful to define completion for a large class of ASP programs and to
automate the process of generating and simplifying completion formulas.
Examining the output produced by this kind of software may help programmers to
see more clearly what their program does, and to what degree its behavior
conforms with their expectations. As a step toward this goal, we propose here a
definition of program completion for a large class of programs in the input
language of the ASP grounder GRINGO, and study its properties. This note is
under consideration for publication in Theory and Practice of Logic
Programming. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Numerical modelling of surface water wave interaction with a moving wall,
Abstract: In the present manuscript, we consider the practical problem of wave
interaction with a vertical wall. However, the novelty here consists in the
fact that the wall can move horizontally due to a system of springs. The water
wave evolution is described with the free surface potential flow model. Then, a
semi-analytical numerical method is presented. It is based on a mapping
technique and a finite difference scheme in the transformed domain. The idea is
to pose the equations on a fixed domain. This method is thoroughly tested and
validated in our study. By choosing specific values of spring parameters, this
system can be used to damp (or in other words to extract the energy of)
incident water waves. | [
1,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: DOPING: Generative Data Augmentation for Unsupervised Anomaly Detection with GAN,
Abstract: Recently, the introduction of the generative adversarial network (GAN) and
its variants has enabled the generation of realistic synthetic samples, which
has been used for enlarging training sets. Previous work primarily focused on
data augmentation for semi-supervised and supervised tasks. In this paper, we
instead focus on unsupervised anomaly detection and propose a novel generative
data augmentation framework optimized for this task. In particular, we propose
to oversample infrequent normal samples - normal samples that occur with small
probability, e.g., rare normal events. We show that these samples are
responsible for false positives in anomaly detection. However, oversampling of
infrequent normal samples is challenging for real-world high-dimensional data
with multimodal distributions. To address this challenge, we propose to use a
GAN variant known as the adversarial autoencoder (AAE) to transform the
high-dimensional multimodal data distributions into low-dimensional unimodal
latent distributions with well-defined tail probability. Then, we
systematically oversample at the `edge' of the latent distributions to increase
the density of infrequent normal samples. We show that our oversampling
pipeline is a unified one: it is generally applicable to datasets with
different complex data distributions. To the best of our knowledge, our method
is the first data augmentation technique focused on improving performance in
unsupervised anomaly detection. We validate our method by demonstrating
consistent improvements across several real-world datasets. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Conditional Variance Penalties and Domain Shift Robustness,
Abstract: When training a deep network for image classification, one can broadly
distinguish between two types of latent features of images that will drive the
classification. Following the notation of Gong et al. (2016), we can divide
latent features into (i) "core" features $X^\text{core}$ whose distribution
$X^\text{core}\vert Y$ does not change substantially across domains and (ii)
"style" features $X^{\text{style}}$ whose distribution $X^{\text{style}}\vert
Y$ can change substantially across domains. These latter orthogonal features
would generally include features such as rotation, image quality or brightness
but also more complex ones like hair color or posture for images of persons.
Guarding against future adversarial domain shifts implies that the influence of
the second type of style features in the prediction has to be limited. We
assume that the domain itself is not observed and hence a latent variable. We
do assume, however, that we can sometimes observe a typically discrete
identifier or $\mathrm{ID}$ variable. We know in some applications, for
example, that two images show the same person, and $\mathrm{ID}$ then refers to
the identity of the person. The method requires only a small fraction of images
to have an $\mathrm{ID}$ variable. We group data samples if they share the same
class and identifier $(Y,\mathrm{ID})=(y,\mathrm{id})$ and penalize the
conditional variance of the prediction if we condition on $(Y,\mathrm{ID})$.
Using this approach is shown to protect against shifts in the distribution of
the style variables for both regression and classification models.
Specifically, the conditional variance penalty CoRe is shown to be equivalent
to minimizing the risk under noise interventions in a regression setting and is
shown to lead to adversarial risk consistency in a partially linear
classification setting. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: The First Optical Spectra of Wolf Rayet Stars in M101 Revealed with Gemini/GMOS,
Abstract: Deep narrow-band HST imaging of the iconic spiral galaxy M101 has revealed
over a thousand new Wolf Rayet (WR) candidates. We report spectrographic
confirmation of 10 HeII emission line sources hosting 15 WR stars. We find WR
stars present at both sub- and super-solar metalicities with WC stars favouring
more metal-rich regions compared to WN stars. We investigate the association of
WR stars with HII regions using archival HST imaging and conclude that the
majority of WR stars are in or associated with HII regions. Of the 10 emission
lines sources, only one appears to be unassociated with a star-forming region.
Our spectroscopic survey provides confidence that our narrow-band photometric
candidates are in fact bonafide WR stars, which will allow us to characterise
the progenitors of any core-collapse supernovae that erupt in the future in
M101. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Topics and Label Propagation: Best of Both Worlds for Weakly Supervised Text Classification,
Abstract: We propose a Label Propagation based algorithm for weakly supervised text
classification. We construct a graph where each document is represented by a
node and edge weights represent similarities among the documents. Additionally,
we discover underlying topics using Latent Dirichlet Allocation (LDA) and
enrich the document graph by including the topics in the form of additional
nodes. The edge weights between a topic and a text document represent level of
"affinity" between them. Our approach does not require document level
labelling, instead it expects manual labels only for topic nodes. This
significantly minimizes the level of supervision needed as only a few topics
are observed to be enough for achieving sufficiently high accuracy. The Label
Propagation Algorithm is employed on this enriched graph to propagate labels
among the nodes. Our approach combines the advantages of Label Propagation
(through document-document similarities) and Topic Modelling (for minimal but
smart supervision). We demonstrate the effectiveness of our approach on various
datasets and compare with state-of-the-art weakly supervised text
classification approaches. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: The Robot Routing Problem for Collecting Aggregate Stochastic Rewards,
Abstract: We propose a new model for formalizing reward collection problems on graphs
with dynamically generated rewards which may appear and disappear based on a
stochastic model. The *robot routing problem* is modeled as a graph whose nodes
are stochastic processes generating potential rewards over discrete time. The
rewards are generated according to the stochastic process, but at each step, an
existing reward disappears with a given probability. The edges in the graph
encode the (unit-distance) paths between the rewards' locations. On visiting a
node, the robot collects the accumulated reward at the node at that time, but
traveling between the nodes takes time. The optimization question asks to
compute an optimal (or epsilon-optimal) path that maximizes the expected
collected rewards.
We consider the finite and infinite-horizon robot routing problems. For
finite-horizon, the goal is to maximize the total expected reward, while for
infinite horizon we consider limit-average objectives. We study the
computational and strategy complexity of these problems, establish NP-lower
bounds and show that optimal strategies require memory in general. We also
provide an algorithm for computing epsilon-optimal infinite paths for arbitrary
epsilon > 0. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Estimating occupation time functionals,
Abstract: We study the estimation of integral type functionals $\int_{0}^{t}f(X_{r})dr$
for a function $f$ and a $d$-dimensional càdlàg process $X$ with respect to
discrete observations by a Riemann-sum estimator. Based on novel semimartingale
approximations in the Fourier domain, central limit theorems are proved for
$L^{2}$-Sobolev functions $f$ with fractional smoothness and continuous Itô
semimartingales $X$. General $L^{2}(\mathbb{P})$-upper bounds on the error for
càdlàg processes are given under weak assumptions. These bounds combine and
generalize all previously obtained results in the literature and apply also to
non-Markovian processes. Several detailed examples are discussed. As
application the approximation of local times for fractional Brownian motion is
studied. The optimality of the $L^{2}(\mathbb{P})$-upper bounds is shown by
proving the corresponding lower bounds in case of Brownian motion. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Feature analysis of multidisciplinary scientific collaboration patterns based on PNAS,
Abstract: The features of collaboration patterns are often considered to be different
from discipline to discipline. Meanwhile, collaborating among disciplines is an
obvious feature emerged in modern scientific research, which incubates several
interdisciplines. The features of collaborations in and among the disciplines
of biological, physical and social sciences are analyzed based on 52,803 papers
published in a multidisciplinary journal PNAS during 1999 to 2013. From those
data, we found similar transitivity and assortativity of collaboration patterns
as well as the identical distribution type of collaborators per author and that
of papers per author, namely a mixture of generalized Poisson and power-law
distributions. In addition, we found that interdisciplinary research is
undertaken by a considerable fraction of authors, not just those with many
collaborators or those with many papers. This case study provides a window for
understanding aspects of multidisciplinary and interdisciplinary collaboration
patterns. | [
1,
1,
0,
0,
0,
0
] | [
"Statistics",
"Quantitative Biology",
"Physics"
] |
Title: Distinction of representations via Bruhat-Tits buildings of p-adic groups,
Abstract: Introductory and pedagogical treatmeant of the article : P. Broussous
"Distinction of the Steinberg representation", with an appendix by François
Courtès, IMRN 2014, no 11, 3140-3157. To appear in Proceedings of Chaire Jean
Morlet, Dipendra Prasad, Volker Heiermann Ed. 2017. Contains modified and
simplified proofs of loc. cit. This article is written in memory of
François Courtès who passed away in september 2016. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Deep Learning for Environmentally Robust Speech Recognition: An Overview of Recent Developments,
Abstract: Eliminating the negative effect of non-stationary environmental noise is a
long-standing research topic for automatic speech recognition that stills
remains an important challenge. Data-driven supervised approaches, including
ones based on deep neural networks, have recently emerged as potential
alternatives to traditional unsupervised approaches and with sufficient
training, can alleviate the shortcomings of the unsupervised methods in various
real-life acoustic environments. In this light, we review recently developed,
representative deep learning approaches for tackling non-stationary additive
and convolutional degradation of speech with the aim of providing guidelines
for those involved in the development of environmentally robust speech
recognition systems. We separately discuss single- and multi-channel techniques
developed for the front-end and back-end of speech recognition systems, as well
as joint front-end and back-end training frameworks. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Random active path model of deep neural networks with diluted binary synapses,
Abstract: Deep learning has become a powerful and popular tool for a variety of machine
learning tasks. However, it is challenging to understand the mechanism of deep
learning from a theoretical perspective. In this work, we propose a random
active path model to study collective properties of deep neural networks with
binary synapses, under the removal perturbation of connections between layers.
In the model, the path from input to output is randomly activated, and the
corresponding input unit constrains the weights along the path into the form of
a $p$-weight interaction glass model. A critical value of the perturbation is
observed to separate a spin glass regime from a paramagnetic regime, with the
transition being of the first order. The paramagnetic phase is conjectured to
have a poor generalization performance. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Super Generalized Central Limit Theorem: Limit distributions for sums of non-identical random variables with power-laws,
Abstract: In nature or societies, the power-law is present ubiquitously, and then it is
important to investigate the mathematical characteristics of power-laws in the
recent era of big data. In this paper we prove the superposition of
non-identical stochastic processes with power-laws converges in density to a
unique stable distribution. This property can be used to explain the
universality of stable laws such that the sums of the logarithmic return of
non-identical stock price fluctuations follow stable distributions. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics",
"Quantitative Finance"
] |
Title: Malaria Likelihood Prediction By Effectively Surveying Households Using Deep Reinforcement Learning,
Abstract: We build a deep reinforcement learning (RL) agent that can predict the
likelihood of an individual testing positive for malaria by asking questions
about their household. The RL agent learns to determine which survey question
to ask next and when to stop to make a prediction about their likelihood of
malaria based on their responses hitherto. The agent incurs a small penalty for
each question asked, and a large reward/penalty for making the correct/wrong
prediction; it thus has to learn to balance the length of the survey with the
accuracy of its final predictions. Our RL agent is a Deep Q-network that learns
a policy directly from the responses to the questions, with an action defined
for each possible survey question and for each possible prediction class. We
focus on Kenya, where malaria is a massive health burden, and train the RL
agent on a dataset of 6481 households from the Kenya Malaria Indicator Survey
2015. To investigate the importance of having survey questions be adaptive to
responses, we compare our RL agent to a supervised learning (SL) baseline that
fixes its set of survey questions a priori. We evaluate on prediction accuracy
and on the number of survey questions asked on a holdout set and find that the
RL agent is able to predict with 80% accuracy, using only 2.5 questions on
average. In addition, the RL agent learns to survey adaptively to responses and
is able to match the SL baseline in prediction accuracy while significantly
reducing survey length. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Quantitative Biology"
] |
Title: A proof of the Muir-Suffridge conjecture for convex maps of the unit ball in $\mathbb C^n$,
Abstract: We prove (and improve) the Muir-Suffridge conjecture for holomorphic convex
maps. Namely, let $F:\mathbb B^n\to \mathbb C^n$ be a univalent map from the
unit ball whose image $D$ is convex. Let $\mathcal S\subset \partial \mathbb
B^n$ be the set of points $\xi$ such that $\lim_{z\to \xi}\|F(z)\|=\infty$.
Then we prove that $\mathcal S$ is either empty, or contains one or two points
and $F$ extends as a homeomorphism $\tilde{F}:\overline{\mathbb B^n}\setminus
\mathcal S\to \overline{D}$. Moreover, $\mathcal S=\emptyset$ if $D$ is
bounded, $\mathcal S$ has one point if $D$ has one connected component at
$\infty$ and $\mathcal S$ has two points if $D$ has two connected components at
$\infty$ and, up to composition with an affine map, $F$ is an extension of the
strip map in the plane to higher dimension. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Evolution of structure, magnetism and electronic transport in doped pyrochlore iridate Y$_2$Ir$_{2-x}$Ru$_{x}$O$_7$,
Abstract: The interplay between spin-orbit coupling (SOC) and electron correlation
($U$) is considered for many exotic phenomena in iridium oxides. We have
investigated the evolution of structural, magnetic and electronic properties in
pyrochlore iridate Y$_2$Ir$_{2-x}$Ru$_{x}$O$_7$ where the substitution of Ru
has been aimed to tune this interplay. The Ru substitution does not introduce
any structural phase transition, however, we do observe an evolution of lattice
parameters with the doping level $x$. X-ray photoemission spectroscopy (XPS)
study indicates Ru adopts charge state of Ru$^{4+}$ and replaces the Ir$^{4+}$
accordingly. Magnetization data reveal both the onset of magnetic
irreversibility and the magnetic moment decreases with progressive substitution
of Ru. These materials show non-equilibrium low temperature magnetic state as
revealed by magnetic relaxation data. Interestingly, we find magnetic
relaxation rate increases with substitution of Ru. The electrical resistivity
shows an insulating behavior in whole temperature range, however, resistivity
decreases with substitution of Ru. Nature of electronic conduction has been
found to follow power-law behavior for all the materials. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Cieliebak's Invariance Theorem and contact structures via connected sums,
Abstract: We present a strong version of Abouzaid's No-Escape Lemma, which allows
varying contact forms on the boundary and which can be used instead of the
Maximum Principle. Moreover, we give a clarified proof of Cieliebak's
Invariance Theorem for Symplectic homology under subcritical handle attachment.
Finally, we introduce the notion of asymptotically finitely generated contact
structures, which states essentially that the Symplectic homology in a certain
degree of any filling of such contact manifolds is uniformly generated by only
finitely many Reeb orbits. This property is then used to show that a large
class of manifolds carries infinitely many exactly fillable contact structures. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Gap Acceptance During Lane Changes by Large-Truck Drivers-An Image-Based Analysis,
Abstract: This paper presents an analysis of rearward gap acceptance characteristics of
drivers of large trucks in highway lane change scenarios. The range between the
vehicles was inferred from camera images using the estimated lane width
obtained from the lane tracking camera as the reference. Six-hundred lane
change events were acquired from a large-scale naturalistic driving data set.
The kinematic variables from the image-based gap analysis were filtered by the
weighted linear least squares in order to extrapolate them at the lane change
time. In addition, the time-to-collision and required deceleration were
computed, and potential safety threshold values are provided. The resulting
range and range rate distributions showed directional discrepancies, i.e., in
left lane changes, large trucks are often slower than other vehicles in the
target lane, whereas they are usually faster in right lane changes. Video
observations have confirmed that major motivations for changing lanes are
different depending on the direction of move, i.e., moving to the left (faster)
lane occurs due to a slower vehicle ahead or a merging vehicle on the
right-hand side, whereas right lane changes are frequently made to return to
the original lane after passing. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Diversity-Sensitive Conditional Generative Adversarial Networks,
Abstract: We propose a simple yet highly effective method that addresses the
mode-collapse problem in the Conditional Generative Adversarial Network (cGAN).
Although conditional distributions are multi-modal (i.e., having many modes) in
practice, most cGAN approaches tend to learn an overly simplified distribution
where an input is always mapped to a single output regardless of variations in
latent code. To address such issue, we propose to explicitly regularize the
generator to produce diverse outputs depending on latent codes. The proposed
regularization is simple, general, and can be easily integrated into most
conditional GAN objectives. Additionally, explicit regularization on generator
allows our method to control a balance between visual quality and diversity. We
demonstrate the effectiveness of our method on three conditional generation
tasks: image-to-image translation, image inpainting, and future video
prediction. We show that simple addition of our regularization to existing
models leads to surprisingly diverse generations, substantially outperforming
the previous approaches for multi-modal conditional generation specifically
designed in each individual task. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: An a Priori Exponential Tail Bound for k-Folds Cross-Validation,
Abstract: We consider a priori generalization bounds developed in terms of
cross-validation estimates and the stability of learners. In particular, we
first derive an exponential Efron-Stein type tail inequality for the
concentration of a general function of n independent random variables. Next,
under some reasonable notion of stability, we use this exponential tail bound
to analyze the concentration of the k-fold cross-validation (KFCV) estimate
around the true risk of a hypothesis generated by a general learning rule.
While the accumulated literature has often attributed this concentration to the
bias and variance of the estimator, our bound attributes this concentration to
the stability of the learning rule and the number of folds k. This insight
raises valid concerns related to the practical use of KFCV and suggests
research directions to obtain reliable empirical estimates of the actual risk. | [
1,
0,
0,
1,
0,
0
] | [
"Statistics",
"Computer Science"
] |
Title: Dex: Incremental Learning for Complex Environments in Deep Reinforcement Learning,
Abstract: This paper introduces Dex, a reinforcement learning environment toolkit
specialized for training and evaluation of continual learning methods as well
as general reinforcement learning problems. We also present the novel continual
learning method of incremental learning, where a challenging environment is
solved using optimal weight initialization learned from first solving a similar
easier environment. We show that incremental learning can produce vastly
superior results than standard methods by providing a strong baseline method
across ten Dex environments. We finally develop a saliency method for
qualitative analysis of reinforcement learning, which shows the impact
incremental learning has on network attention. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: The first order partial differential equations resolved with any derivatives,
Abstract: In this paper we discuss the first order partial differential equations
resolved with any derivatives. At first, we transform the first order partial
differential equation resolved with respect to a time derivative into a system
of linear equations. Secondly, we convert it into a system of the first order
linear partial differential equations with constant coefficients and nonlinear
algebraic equations. Thirdly, we solve them by the Fourier transform and
convert them into the equivalent integral equations. At last, we extend to
discuss the first order partial differential equations resolved with respect to
time derivatives and the general scenario resolved with any derivatives. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Real Time Collision Detection and Identification for Robotic Manipulators,
Abstract: The majority of everyday tasks involve interacting with unstructured
environments. This implies that, in order for robots to be truly useful they
must be able to handle contacts. This paper explores how a particle filter can
be used to localize a contact point and estimate the external force. We
demonstrate the capability of the particle filter on a simulated 4DoF planar
robotic arm, and compare it to a well-established analytical approach. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: A multiple timescales approach to bridging spiking- and population-level dynamics,
Abstract: A rigorous bridge between spiking-level and macroscopic quantities is an
on-going and well-developed story for asynchronously firing neurons, but focus
has shifted to include neural populations exhibiting varying synchronous
dynamics. Recent literature has used the Ott--Antonsen ansatz (2008) to great
effect, allowing a rigorous derivation of an order parameter for large
oscillator populations. The ansatz has been successfully applied using several
models including networks of Kuramoto oscillators, theta models, and
integrate-and-fire neurons, along with many types of network topologies. In the
present study, we take a converse approach: given the mean field dynamics of
slow synapses, predict the synchronization properties of finite neural
populations. The slow synapse assumption is amenable to averaging theory and
the method of multiple timescales. Our proposed theory applies to two
heterogeneous populations of N excitatory n-dimensional and N inhibitory
m-dimensional oscillators with homogeneous synaptic weights. We then
demonstrate our theory using two examples. In the first example we take a
network of excitatory and inhibitory theta neurons and consider the case with
and without heterogeneous inputs. In the second example we use Traub models
with calcium for the excitatory neurons and Wang-Buzs{á}ki models for the
inhibitory neurons. We accurately predict phase drift and phase locking in each
example even when the slow synapses exhibit non-trivial mean-field dynamics. | [
0,
0,
0,
0,
1,
0
] | [
"Quantitative Biology",
"Mathematics"
] |
Title: Sentiment Identification in Code-Mixed Social Media Text,
Abstract: Sentiment analysis is the Natural Language Processing (NLP) task dealing with
the detection and classification of sentiments in texts. While some tasks deal
with identifying the presence of sentiment in the text (Subjectivity analysis),
other tasks aim at determining the polarity of the text categorizing them as
positive, negative and neutral. Whenever there is a presence of sentiment in
the text, it has a source (people, group of people or any entity) and the
sentiment is directed towards some entity, object, event or person. Sentiment
analysis tasks aim to determine the subject, the target and the polarity or
valence of the sentiment. In our work, we try to automatically extract
sentiment (positive or negative) from Facebook posts using a machine learning
approach.While some works have been done in code-mixed social media data and in
sentiment analysis separately, our work is the first attempt (as of now) which
aims at performing sentiment analysis of code-mixed social media text. We have
used extensive pre-processing to remove noise from raw text. Multilayer
Perceptron model has been used to determine the polarity of the sentiment. We
have also developed the corpus for this task by manually labeling Facebook
posts with their associated sentiments. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Microscopic theory of refractive index applied to metamaterials: Effective current response tensor corresponding to standard relation $n^2 = \varepsilon_{\mathrm{eff}} μ_{\mathrm{eff}}$,
Abstract: In this article, we first derive the wavevector- and frequency-dependent,
microscopic current response tensor which corresponds to the "macroscopic"
ansatz $\vec D = \varepsilon_0 \varepsilon_{\mathrm{eff}} \vec E$ and $\vec B =
\mu_0 \mu_{\mathrm{eff}} \vec H$ with wavevector- and frequency-independent,
"effective" material constants $\varepsilon_{\mathrm{eff}}$ and
$\mu_{\mathrm{eff}}$. We then deduce the electromagnetic and optical properties
of this effective material model by employing exact, microscopic response
relations. In particular, we argue that for recovering the standard relation
$n^2 = \varepsilon_{\mathrm{eff}} \mu_{\mathrm{eff}}$ between the refractive
index and the effective material constants, it is imperative to start from the
microscopic wave equation in terms of the transverse dielectric function,
$\varepsilon_{\mathrm{T}}(\vec k, \omega) = 0$. On the phenomenological side,
our result is especially relevant for metamaterials research, which draws
directly on the standard relation for the refractive index in terms of
effective material constants. Since for a wide class of materials the current
response tensor can be calculated from first principles and compared to the
model expression derived here, this work also paves the way for a systematic
search for new metamaterials. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Semidefinite Relaxation-Based Optimization of Multiple-Input Wireless Power Transfer Systems,
Abstract: An optimization procedure for multi-transmitter (MISO) wireless power
transfer (WPT) systems based on tight semidefinite relaxation (SDR) is
presented. This method ensures physical realizability of MISO WPT systems
designed via convex optimization -- a robust, semi-analytical and intuitive
route to optimizing such systems. To that end, the nonconvex constraints
requiring that power is fed into rather than drawn from the system via all
transmitter ports are incorporated in a convex semidefinite relaxation, which
is efficiently and reliably solvable by dedicated algorithms. A test of the
solution then confirms that this modified problem is equivalent (tight
relaxation) to the original (nonconvex) one and that the true global optimum
has been found. This is a clear advantage over global optimization methods
(e.g. genetic algorithms), where convergence to the true global optimum cannot
be ensured or tested. Discussions of numerical results yielded by both the
closed-form expressions and the refined technique illustrate the importance and
practicability of the new method. It, is shown that this technique offers a
rigorous optimization framework for a broad range of current and emerging WPT
applications. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Counterfactual Reasoning with Disjunctive Knowledge in a Linear Structural Equation Model,
Abstract: We consider the problem of estimating counterfactual quantities when prior
knowledge is available in the form of disjunctive statements. These include
disjunction of conditions (e.g., "the patient is more than 60 years of age") as
well as disjuction of antecedants (e.g., "had the patient taken either drug A
or drug B"). Focusing on linear structural equation models (SEM) and imperfect
control plans, we extend the counterfactual framework of Balke and Pearl (1995)
, Chen and Pearl (2015), and Pearl (2009, pp. 389-391) from unconditional to
conditional plans, from a univariate treatment to a set of treatments, and from
point type knowledge to disjunctive knowledge. Finally, we provide improved
matrix representations of the resulting counterfactual parameters, and improved
computational methods of their evaluation. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Neighborhood selection with application to social networks,
Abstract: The topic of this paper is modeling and analyzing dependence in stochastic
social networks. Using a latent variable block model allows the analysis of
dependence between blocks via the analysis of a latent graphical model. Our
approach to the analysis of the graphical model then is based on the idea
underlying the neighborhood selection scheme put forward by Meinshausen and
Bühlmann (2006). However, because of the latent nature of our model,
estimates have to be used in lieu of the unobserved variables. This leads to a
novel analysis of graphical models under uncertainty, in the spirit of
Rosenbaum et al. (2010), or Belloni et al. (2017). Lasso-based selectors, and a
class of Dantzig-type selectors are studied. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics",
"Computer Science"
] |
Title: Average-radius list-recovery of random linear codes: it really ties the room together,
Abstract: We analyze the list-decodability, and related notions, of random linear
codes. This has been studied extensively before: there are many different
parameter regimes and many different variants. Previous works have used
complementary styles of arguments---which each work in their own parameter
regimes but not in others---and moreover have left some gaps in our
understanding of the list-decodability of random linear codes. In particular,
none of these arguments work well for list-recovery, a generalization of
list-decoding that has been useful in a variety of settings.
In this work, we present a new approach, which works across parameter regimes
and further generalizes to list-recovery. Our main theorem can establish better
list-decoding and list-recovery results for low-rate random linear codes over
large fields; list-recovery of high-rate random linear codes; and it can
recover the rate bounds of Guruswami, Hastad, and Kopparty for constant-rate
random linear codes (although with large list sizes). | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: From Dirac semimetals to topological phases in three dimensions: a coupled wire construction,
Abstract: Weyl and Dirac (semi)metals in three dimensions have robust gapless
electronic band structures. Their massless single-body energy spectra are
protected by symmetries such as lattice translation, (screw) rotation and time
reversal. In this manuscript, we discuss many-body interactions in these
systems. We focus on strong interactions that preserve symmetries and are
outside the single-body mean-field regime. By mapping a Dirac (semi)metal to a
model based on a three dimensional array of coupled Dirac wires, we show (1)
the Dirac (semi)metal can acquire a many-body excitation energy gap without
breaking the relevant symmetries, and (2) interaction can enable an anomalous
Weyl (semi)metallic phase that is otherwise forbidden by symmetries in the
single-body setting and can only be present holographically on the boundary of
a four dimensional weak topological insulator. Both of these topological states
support fractional gapped (gapless) bulk (resp. boundary) quasiparticle
excitations. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Generalization of Special Functions and its Applications to Multiplicative and Ordinary Fractional Derivatives,
Abstract: The goal of this paper is to extend the classical and multiplicative
fractional derivatives. For this purpose, it is introduced the new extended
modified Bessel function and also given an important relation between this new
function I(v,q;x) and the confluent hypergeometric function. Besides, it is
used to generalize the hypergeometric, the confluent hypergeometric and the
extended beta functions by using the new extended modified Bessel function.
Also, the asymptotic formulae and the generating function of the extended
modified Bessel function are obtained. The extensions of classical and
multiplicative fractional derivatives are defined via extended modified Bessel
function and, first time the fractional derivative of rational functions is
explicitly given via complex partial fraction decomposition. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Adaptive clustering procedure for continuous gravitational wave searches,
Abstract: In hierarchical searches for continuous gravitational waves, clustering of
candidates is an important postprocessing step because it reduces the number of
noise candidates that are followed-up at successive stages [1][7][12]. Previous
clustering procedures bundled together nearby candidates ascribing them to the
same root cause (be it a signal or a disturbance), based on a predefined
cluster volume. In this paper, we present a procedure that adapts the cluster
volume to the data itself and checks for consistency of such volume with what
is expected from a signal. This significantly improves the noise rejection
capabilities at fixed detection threshold, and at fixed computing resources for
the follow-up stages, this results in an overall more sensitive search. This
new procedure was employed in the first Einstein@Home search on data from the
first science run of the advanced LIGO detectors (O1) [11]. | [
0,
1,
1,
0,
0,
0
] | [
"Physics",
"Statistics"
] |