context: It is likely that John moved to the garden. We believe that Lily is a rhino. We doubt that Mary got the apple. It is probably not the case that if either 'Lily is a rhino' or 'John moved to the garden' but not both then Julius is white. Chances are slight that if either 'Mary got the apple' or 'Lily is a rhino' but not both then Gertrude is a cat. We doubt that if 'Mary got the apple' or 'John moved to the garden' or both then Jeff discarded the milk.
hypothesis: It is impossible that 'Gertrude is a cat and Mary got the apple'.
valid_hypothesis: It is impossible that 'Gertrude is a cat and Mary got the apple'.
invalid_hypothesis: There is a better than even chance that 'Gertrude is a cat and Mary got the apple'.
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.
    0.75::factB.
    0.2::factC.
    %hop1
    0.25::factX:-xor(factB,factA).
    0.1::factY:-xor(factC,factB).
    0.2::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-and(factY,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Gertrude is a cat and Mary got the apple'.