context: It is probably not the case that Emily is a cat. There is a very good chance that Gertrude is a sheep. It is certain that Brian is yellow. There is almost no chance that if 'Brian is yellow' or 'Gertrude is a sheep' or both then Fred is in the office. There is almost no chance that if either 'Emily is a cat' or 'Gertrude is a sheep' but not both then John took the apple. It is unlikely that if 'Emily is a cat' or 'Gertrude is a sheep' or both then Bernhard is gray.
hypothesis: There is a very good chance that 'Brian is yellow and Gertrude is a sheep'.
valid_hypothesis: There is a very good chance that 'Brian is yellow and Gertrude is a sheep'.
invalid_hypothesis: It is highly unlikely that 'Brian is yellow and Gertrude is a sheep'.
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
    0.25::factA.
    0.8::factB.
    1.0::factC.
    %hop1
    0.02::factX:-or(factC,factB).
    0.02::factY:-xor(factA,factB).
    0.2::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is yellow and Gertrude is a sheep'.