context: We believe that Julius is a lion. We doubt that Gertrude is a cat. It is unlikely that Bernhard is a rhino. It is unlikely that if 'Gertrude is a cat' or 'Bernhard is a rhino' or both then Greg is a swan. It is almost certain that if 'Julius is a lion and Bernhard is a rhino' then Lily is yellow. It is almost certain that if 'Gertrude is a cat' or 'Bernhard is a rhino' or both then John picked up the milk.
hypothesis: There is a better than even chance that 'Julius is a lion and Lily is yellow'.
valid_hypothesis: Chances are slight that 'Julius is a lion and Lily is yellow'.
invalid_hypothesis: There is a better than even chance that 'Julius is a lion and Lily is yellow'.
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
    0.75::factA.
    0.2::factB.
    0.2::factC.
    %hop1
    0.2::factX:-or(factB,factC).
    0.95::factY:-and(factA,factC).
    0.95::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-and(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a lion and Lily is yellow'.