context: There is little chance that Mary went to the bedroom. There is a very good chance that Gertrude is a cat. We believe that Julius is a rhino. There is a very good chance that if either 'Gertrude is a cat' or 'Mary went to the bedroom' but not both then Lily is yellow. There is a very good chance that if either 'Mary went to the bedroom' or 'Julius is a rhino' but not both then Greg is yellow. It is almost certain that if either 'Mary went to the bedroom' or 'Julius is a rhino' but not both then John picked up the milk.
hypothesis: It is highly likely that 'Gertrude is a cat' or 'Greg is yellow' or both.
valid_hypothesis: It is highly likely that 'Gertrude is a cat' or 'Greg is yellow' or both.
invalid_hypothesis: Chances are slight that 'Gertrude is a cat' or 'Greg is yellow' or 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
    0.1::factA.
    0.8::factB.
    0.75::factC.
    %hop1
    0.8::factX:-xor(factB,factA).
    0.8::factY:-xor(factA,factC).
    0.95::factZ:-xor(factA,factC).
  
    %hop2
    conclusion:-or(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Gertrude is a cat' or 'Greg is yellow' or both.