Datasets:

Modalities:
Text
Languages:
English
Libraries:
Datasets
License:
File size: 12,286 Bytes
4365a98
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
(* ========================================================================= *)
(* Basic definitions for and theorems about term rewriting.                  *)
(* ========================================================================= *)

let TRS_RULES,TRS_INDUCT,TRS_CASES = new_inductive_definition
  `(!i l r.
         (l,r) IN rws ==> TRS rws (termsubst i l) (termsubst i r)) /\
   (!s t f largs rargs.
         TRS rws s t ==> TRS rws (Fn f (APPEND largs (CONS s rargs)))
                                 (Fn f (APPEND largs (CONS t rargs))))`;;

(* ------------------------------------------------------------------------- *)
(* Nice general result justfying both deletion and right-simplification.     *)
(* ------------------------------------------------------------------------- *)

let CONVERGENT_MODIFY_LEMMA = prove
 (`!R S. SN R /\
         CR(RTC R) /\
         (!x y. S x y ==> TC R x y) /\
         (!x y. R x y ==> ?y'. S x y')
         ==> !y:A. NORMAL(R) y ==> !x. RTC R x y ==> RTC S x y`,
  REPEAT GEN_TAC THEN ONCE_REWRITE_TAC[GSYM SN_TC] THEN
  REWRITE_TAC[SN_NOETHERIAN] THEN STRIP_TAC THEN
  GEN_TAC THEN REWRITE_TAC[NORMAL; NOT_EXISTS_THM] THEN DISCH_TAC THEN
  FIRST_ASSUM MATCH_MP_TAC THEN X_GEN_TAC `x:A` THEN DISCH_TAC THEN
  GEN_REWRITE_TAC LAND_CONV [RTC_CASES_R] THEN
  DISCH_THEN(DISJ_CASES_THEN2 SUBST1_TAC MP_TAC) THEN
  REWRITE_TAC[RTC_REFL] THEN
  DISCH_THEN(X_CHOOSE_THEN `u:A` STRIP_ASSUME_TAC) THEN
  UNDISCH_TAC `!x:A y:A. R x y ==> (?y':A. S x y')` THEN
  DISCH_THEN(MP_TAC o SPECL [`x:A`; `u:A`]) THEN
  ASM_REWRITE_TAC[] THEN DISCH_THEN(X_CHOOSE_TAC `v:A`) THEN
  FIRST_X_ASSUM(MP_TAC o SPECL [`x:A`; `v:A`]) THEN ASM_REWRITE_TAC[] THEN
  DISCH_TAC THEN FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [CR]) THEN
  DISCH_THEN(MP_TAC o SPECL [`x:A`; `y:A`; `v:A`]) THEN
  ASM_REWRITE_TAC[] THEN ANTS_TAC THENL
   [ASM_MESON_TAC[RTC_CASES_R; TC_RTC_CASES_R]; ALL_TAC] THEN
  DISCH_THEN(X_CHOOSE_THEN `z:A` STRIP_ASSUME_TAC) THEN
  SUBGOAL_THEN `z:A = y` SUBST_ALL_TAC THEN ASM_MESON_TAC[RTC_CASES_R]);;

let CONVERGENT_MODIFY = prove
 (`!R S. SN R /\
         CR(RTC R) /\
         (!x:A y. S x y ==> TC R x y) /\
         (!x:A y. R x y ==> ?y'. S x y')
         ==> SN(S) /\ CR(RTC S)`,
  REPEAT GEN_TAC THEN STRIP_TAC THEN
  MATCH_MP_TAC(TAUT `a /\ (a ==> b) ==> a /\ b`) THEN CONJ_TAC THENL
   [ONCE_REWRITE_TAC[SN_WF] THEN MATCH_MP_TAC WF_SUBSET THEN
    EXISTS_TAC `INV(TC(R:A->A->bool))` THEN ASM_REWRITE_TAC[INV] THEN
    REWRITE_TAC[GSYM TC_INV; WF_TC] THEN ASM_REWRITE_TAC[GSYM SN_WF];
    ALL_TAC] THEN
  DISCH_TAC THEN MATCH_MP_TAC NEWMAN_LEMMA THEN ASM_REWRITE_TAC[WCR] THEN
  MAP_EVERY X_GEN_TAC [`x:A`; `y1:A`; `y2:A`] THEN STRIP_TAC THEN
  FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [CR]) THEN
  DISCH_THEN(MP_TAC o SPECL [`x:A`; `y1:A`; `y2:A`]) THEN ANTS_TAC THENL
   [ASM_MESON_TAC[RTC_INC_TC]; ALL_TAC] THEN
  DISCH_THEN(X_CHOOSE_THEN `z0:A` STRIP_ASSUME_TAC) THEN
  MP_TAC(MATCH_MP SN_WN (ASSUME `SN(R:A->A->bool)`)) THEN
  REWRITE_TAC[WN] THEN DISCH_THEN(MP_TAC o SPEC `z0:A`) THEN
  DISCH_THEN(X_CHOOSE_THEN `z:A` STRIP_ASSUME_TAC) THEN
  MP_TAC(SPECL [`R:A->A->bool`; `S:A->A->bool`] CONVERGENT_MODIFY_LEMMA) THEN
  ASM_REWRITE_TAC[] THEN ASM_MESON_TAC[RTC_TRANS]);;

let EQUIVALENT_JOINABLE_MODIFY = prove
 (`!R S. SN R /\
         CR(RTC R) /\
         (!x y. S x y ==> TC R x y) /\
         (!x y. R x y ==> ?y'. S x y')
         ==> (!x:A y. JOINABLE S x y = JOINABLE R x y)`,
  REPEAT STRIP_TAC THEN REWRITE_TAC[JOINABLE] THEN EQ_TAC THEN
  DISCH_THEN(X_CHOOSE_THEN `z:A` STRIP_ASSUME_TAC) THENL
   [SUBGOAL_THEN `!x:A y. RTC S x y ==> RTC R x y`
     (fun th -> ASM_MESON_TAC[th]) THEN
    REWRITE_TAC[RTC; RC_CASES] THEN
    SUBGOAL_THEN `!x:A y. TC S x y ==> TC R x y`
     (fun th -> ASM_MESON_TAC[th]) THEN
    GEN_REWRITE_TAC (funpow 2 BINDER_CONV o RAND_CONV o ONCE_DEPTH_CONV)
     [GSYM TC_IDEMP] THEN
    MATCH_MP_TAC TC_MONO THEN ASM_REWRITE_TAC[];
    FIRST_ASSUM(MP_TAC o MATCH_MP SN_WN) THEN REWRITE_TAC[WN] THEN
    DISCH_THEN(MP_TAC o SPEC `z:A`) THEN
    DISCH_THEN(X_CHOOSE_THEN `w:A` STRIP_ASSUME_TAC) THEN
    MP_TAC(SPECL [`R:A->A->bool`; `S:A->A->bool`] CONVERGENT_MODIFY_LEMMA) THEN
    ASM_REWRITE_TAC[] THEN
    DISCH_THEN(MP_TAC o SPEC `w:A`) THEN ASM_REWRITE_TAC[] THEN
    ASM_MESON_TAC[RTC_TRANS]]);;

let EQUIVALENT_RSTC_MODIFY = prove
 (`!R S. SN R /\
         CR(RTC R) /\
         (!x y. S x y ==> TC R x y) /\
         (!x y. R x y ==> ?y'. S x y')
         ==> (!x:A y. RSTC S x y = RSTC R x y)`,
  REPEAT STRIP_TAC THEN
  MP_TAC(SPECL [`R:A->A->bool`; `S:A->A->bool`] CONVERGENT_MODIFY) THEN
  ASM_REWRITE_TAC[] THEN
  MP_TAC(SPECL [`R:A->A->bool`; `S:A->A->bool`]
               EQUIVALENT_JOINABLE_MODIFY) THEN
  ASM_SIMP_TAC[CR_RSTC_JOINABLE] THEN
  ASM_REWRITE_TAC[] THEN ASM_SIMP_TAC[]);;

let EQUIVALENT_MODIFY = prove
 (`!R S. SN R /\
         CR(RTC R) /\
         (!x y. S x y ==> TC R x y) /\
         (!x y. R x y ==> ?y'. S x y')
         ==> SN(S) /\ CR(RTC S) /\ (!x:A y. RSTC S x y = RSTC R x y)`,
  REPEAT GEN_TAC THEN STRIP_TAC THEN
  REWRITE_TAC[CONJ_ASSOC] THEN CONJ_TAC THENL
   [MATCH_MP_TAC CONVERGENT_MODIFY THEN EXISTS_TAC `R:A->A->bool`;
    MATCH_MP_TAC EQUIVALENT_RSTC_MODIFY] THEN
  ASM_REWRITE_TAC[]);;

(* ------------------------------------------------------------------------- *)
(* Special case of right simplification of rules.                            *)
(* ------------------------------------------------------------------------- *)

let EQUIVALENT_MODIFY_RIGHT = prove
 (`!R S S'.
        SN(\x y. R x y \/ S x y) /\
        CR(RTC(\x y. R x y \/ S x y)) /\
        (!s:A t. S s t ==> ?t'. S' s t') /\
        (!s t. S' s t ==> ?u. S s u /\ RTC (\x y. R x y \/ S x y) u t)
        ==> SN(\x y. R x y \/ S' x y) /\
            CR(RTC(\x y. R x y \/ S' x y)) /\
            (!x y. RSTC(\x y. R x y \/ S' x y) x y =
                   RSTC(\x y. R x y \/ S x y) x y)`,
  REPEAT GEN_TAC THEN STRIP_TAC THEN MATCH_MP_TAC EQUIVALENT_MODIFY THEN
  ASM_REWRITE_TAC[] THEN CONJ_TAC THEN
  MAP_EVERY X_GEN_TAC [`x:A`; `y:A`] THEN STRIP_TAC THENL
   [MATCH_MP_TAC TC_INC THEN ASM_REWRITE_TAC[];
    FIRST_ASSUM(MP_TAC o C MATCH_MP (ASSUME `(S':A->A->bool) x y`)) THEN
    DISCH_THEN(X_CHOOSE_THEN `u:A` STRIP_ASSUME_TAC) THEN
    GEN_REWRITE_TAC I [TC_RTC_CASES_R] THEN
    EXISTS_TAC `u:A` THEN ASM_REWRITE_TAC[];
    ASM_MESON_TAC[];
    ASM_MESON_TAC[]]);;

(* ------------------------------------------------------------------------- *)
(* And of deletion of joinable ones.                                         *)
(* ------------------------------------------------------------------------- *)

let CONVERGENT_DELETE_LEFT = prove
 (`!R S. SN(\x y. R x y \/ S x y) /\
         CR(RTC(\x y. R x y \/ S x y)) /\
         (!x:A y. S x y ==> ?z. R x z)
         ==> SN(R) /\ CR(RTC R) /\
             (!x y. RSTC(R) x y = RSTC(\x y. R x y \/ S x y) x y)`,
  REPEAT GEN_TAC THEN STRIP_TAC THEN MATCH_MP_TAC EQUIVALENT_MODIFY THEN
  ASM_REWRITE_TAC[] THEN CONJ_TAC THEN
  MAP_EVERY X_GEN_TAC [`x:A`; `y:A`] THEN DISCH_TAC THEN
  ASM_SIMP_TAC[TC_INC] THEN ASM_MESON_TAC[]);;

(* ------------------------------------------------------------------------- *)
(* The case of left-simplification is harder; this lemma isn't enough.       *)
(* But given the deletion result above, we don't need this anyway!           *)
(* ------------------------------------------------------------------------- *)

let CONVERGENT_MODIFY_LEMMA = prove
 (`!R S S' t.
        SN(\x y. R x y \/ S x y \/ S' x y) /\
        CR(RTC(\x y. R x y \/ S x y)) /\
        (!s t. S s t
               ==> ?s' t'. RTC R s s' /\ RTC R t t' /\
                           (S' s' t' \/ S' t' s')) /\
        NORMAL(\x y. R x y \/ S x y) t
        ==> !s:A. RTC (\x y. R x y \/ S x y) s t
                  ==> RTC (\x y. R x y \/ S' x y) s t`,
  REPEAT GEN_TAC THEN ONCE_REWRITE_TAC[GSYM SN_TC] THEN
  REWRITE_TAC[SN_NOETHERIAN] THEN STRIP_TAC THEN FIRST_ASSUM MATCH_MP_TAC THEN
  X_GEN_TAC `s:A` THEN DISCH_TAC THEN
  GEN_REWRITE_TAC LAND_CONV [RTC_CASES_R] THEN
  DISCH_THEN(DISJ_CASES_THEN2 SUBST1_TAC MP_TAC) THEN
  REWRITE_TAC[RTC_REFL] THEN
  DISCH_THEN(X_CHOOSE_THEN `u:A` STRIP_ASSUME_TAC) THENL
   [FIRST_ASSUM(fun th -> MP_TAC(SPEC `u:A` th) THEN ANTS_TAC) THENL
     [ONCE_REWRITE_TAC[TC_CASES_R] THEN ASM_REWRITE_TAC[]; ALL_TAC] THEN
    ASM_REWRITE_TAC[] THEN DISCH_TAC THEN ONCE_REWRITE_TAC[RTC_CASES_R] THEN
    DISJ2_TAC THEN EXISTS_TAC `u:A` THEN ASM_REWRITE_TAC[]; ALL_TAC] THEN
  FIRST_X_ASSUM(MP_TAC o SPECL [`s:A`; `u:A`]) THEN ASM_REWRITE_TAC[] THEN
  REWRITE_TAC[LEFT_IMP_EXISTS_THM] THEN
  MAP_EVERY X_GEN_TAC [`s':A`; `u':A`] THEN STRIP_TAC THENL
   [FIRST_ASSUM(MP_TAC o SPEC `u':A`) THEN ANTS_TAC THENL
     [ONCE_REWRITE_TAC[TC_RTC_CASES_R] THEN EXISTS_TAC `u:A` THEN
      ASM_REWRITE_TAC[] THEN UNDISCH_TAC `RTC R (u:A) u'` THEN
      MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`u':A`; `u:A`] THEN
      MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[]; ALL_TAC] THEN
    FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [CR]) THEN
    DISCH_THEN(MP_TAC o SPECL [`s:A`; `u':A`; `t:A`]) THEN
    ANTS_TAC THENL
     [CONJ_TAC THENL
       [ONCE_REWRITE_TAC[RTC_CASES_R] THEN DISJ2_TAC THEN EXISTS_TAC `u:A` THEN
        ASM_REWRITE_TAC[] THEN
        UNDISCH_TAC `RTC R (u:A) u'` THEN
        MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`u':A`; `u:A`] THEN
        MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[];
        ALL_TAC] THEN
      ONCE_REWRITE_TAC[RTC_CASES_R] THEN DISJ2_TAC THEN EXISTS_TAC `u:A` THEN
      ASM_REWRITE_TAC[];
      ALL_TAC] THEN
    DISCH_THEN(X_CHOOSE_THEN `z:A` STRIP_ASSUME_TAC) THEN
    SUBGOAL_THEN `z:A = t` SUBST_ALL_TAC THENL
     [UNDISCH_TAC `RTC (\x y. R x y \/ S x y) t (z:A)` THEN
      ONCE_REWRITE_TAC[RTC_CASES_R] THEN
      ASM_CASES_TAC `z:A = t` THEN ASM_REWRITE_TAC[] THEN
      FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [NORMAL]) THEN
      REWRITE_TAC[] THEN MESON_TAC[]; ALL_TAC] THEN
    ASM_REWRITE_TAC[] THEN DISCH_TAC THEN
    ONCE_REWRITE_TAC[RTC_CASES] THEN DISJ2_TAC THEN
    EXISTS_TAC `u':A` THEN ASM_REWRITE_TAC[] THEN
    ONCE_REWRITE_TAC[RTC_CASES_L] THEN DISJ2_TAC THEN
    EXISTS_TAC `s':A` THEN ASM_REWRITE_TAC[] THEN
    UNDISCH_TAC `RTC R (s:A) s'` THEN
    MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`s':A`; `s:A`] THEN
    MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[]; ALL_TAC] THEN
  ASM_CASES_TAC `s':A = s` THENL
   [RULE_ASSUM_TAC(REWRITE_RULE[GSYM SN_NOETHERIAN; SN_WF]) THEN
    FIRST_ASSUM(MP_TAC o MATCH_MP WF_REFL) THEN
    DISCH_THEN(MP_TAC o SPEC `s:A`) THEN REWRITE_TAC[INV] THEN
    MATCH_MP_TAC(TAUT `a ==> ~a ==> b`) THEN
    ONCE_REWRITE_TAC[TC_RTC_CASES_R] THEN EXISTS_TAC `u:A` THEN
    ASM_REWRITE_TAC[] THEN
    ONCE_REWRITE_TAC[RTC_CASES_L] THEN DISJ2_TAC THEN EXISTS_TAC `u':A` THEN
    UNDISCH_THEN `s':A = s` SUBST_ALL_TAC THEN ASM_REWRITE_TAC[] THEN
    UNDISCH_TAC `RTC R (u:A) u'` THEN
    MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`u':A`; `u:A`] THEN
    MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[]; ALL_TAC] THEN
  FIRST_ASSUM(MP_TAC o SPEC `s':A`) THEN ANTS_TAC THENL
   [MATCH_MP_TAC RTC_NE_IMP_TC THEN ASM_REWRITE_TAC[] THEN
    UNDISCH_TAC `RTC R (s:A) s'` THEN
    MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`s':A`; `s:A`] THEN
    MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[]; ALL_TAC] THEN
  FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [CR]) THEN
  DISCH_THEN(MP_TAC o SPECL [`s:A`; `s':A`; `t:A`]) THEN
  ANTS_TAC THENL
   [CONJ_TAC THENL
     [UNDISCH_TAC `RTC R (s:A) s'` THEN
      MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`s':A`; `s:A`] THEN
      MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[];
      ONCE_REWRITE_TAC[RTC_CASES_R] THEN DISJ2_TAC THEN EXISTS_TAC `u:A` THEN
      ASM_REWRITE_TAC[]];
    ALL_TAC] THEN
  DISCH_THEN(X_CHOOSE_THEN `z:A` STRIP_ASSUME_TAC) THEN
  SUBGOAL_THEN `z:A = t` SUBST_ALL_TAC THENL
   [UNDISCH_TAC `RTC (\x y. R x y \/ S x y) t (z:A)` THEN
    ONCE_REWRITE_TAC[RTC_CASES_R] THEN
    ASM_CASES_TAC `z:A = t` THEN ASM_REWRITE_TAC[] THEN
    FIRST_ASSUM(MP_TAC o GEN_REWRITE_RULE I [NORMAL]) THEN
    REWRITE_TAC[] THEN MESON_TAC[]; ALL_TAC] THEN
  ASM_REWRITE_TAC[] THEN DISCH_TAC THEN
  ONCE_REWRITE_TAC[RTC_CASES] THEN DISJ2_TAC THEN
  EXISTS_TAC `s':A` THEN ASM_REWRITE_TAC[] THEN
  UNDISCH_TAC `RTC R (s:A) s'` THEN
  MAP_EVERY (fun s -> SPEC_TAC(s,s)) [`s':A`; `s:A`] THEN
  MATCH_MP_TAC RTC_MONO THEN SIMP_TAC[]);;