context: It is likely that Jeff went to the bedroom. It is unlikely that Bernhard is a rhino. We believe that Lily is a lion. It is highly unlikely that if either 'Lily is a lion' or 'Bernhard is a rhino' but not both then Mary took the milk. There is a better than even chance that if either 'Bernhard is a rhino' or 'Lily is a lion' but not both then Sandra left the apple. It is highly unlikely that if 'Bernhard is a rhino' or 'Jeff went to the bedroom' or both then Julius is a frog.
hypothesis: It is highly unlikely that either 'Bernhard is a rhino' or 'Sandra left the apple' but not both.
valid_hypothesis: Chances are about even that either 'Bernhard is a rhino' or 'Sandra left the apple' but not both.
invalid_hypothesis: It is highly unlikely that either 'Bernhard is a rhino' or 'Sandra left the apple' but not both.
problog: 
    and(A,B) :- A,B.
    or(A,B) :- A;B.
    nand(A,B) :- not(and(A,B)).
    nor(A,B) :- not(or(A,B)).
    xor(A,B) :- or(A,B), nand(A,B).
  
    %hop0
    0.7::factA.
    0.2::factB.
    0.75::factC.
    %hop1
    0.05::factX:-xor(factC,factB).
    0.6::factY:-xor(factB,factC).
    0.05::factZ:-or(factB,factA).
  
    %hop2
    conclusion:-xor(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Bernhard is a rhino' or 'Sandra left the apple' but not both.