context: It is improbable that Sandra left the milk. It is probably not the case that Greg is white. There is almost no chance that Mary dropped the milk. It is improbable that if either 'Mary dropped the milk' or 'Sandra left the milk' but not both then Gertrude is a wolf. Chances are slight that if 'Mary dropped the milk' or 'Greg is white' or both then Lily is a lion. It is highly unlikely that if 'Greg is white' or 'Mary dropped the milk' or both then Jessica is a sheep.
hypothesis: We believe that 'Jessica is a sheep' or 'Lily is a lion' or both.
valid_hypothesis: It is highly unlikely that 'Jessica is a sheep' or 'Lily is a lion' or both.
invalid_hypothesis: We believe that 'Jessica is a sheep' or 'Lily is a lion' 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.
    0.25::factB.
    0.02::factC.
    %hop1
    0.1::factX:-xor(factC,factA).
    0.1::factY:-or(factC,factB).
    0.05::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-or(factZ,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Jessica is a sheep' or 'Lily is a lion' or both.