context: It is likely that Greg is white. We believe that Julius is a lion. Chances are slight that Brian is yellow. It is probably the case that if either 'Julius is a lion' or 'Greg is white' but not both then Winona is a wolf. It is unlikely that if 'Julius is a lion and Greg is white' then Sandra left the milk. Chances are about even that if 'Greg is white and Julius is a lion' then Bernhard is white.
hypothesis: It is unlikely that 'Winona is a wolf and Julius is a lion'.
valid_hypothesis: It is unlikely that 'Winona is a wolf and Julius is a lion'.
invalid_hypothesis: It is probably the case that 'Winona is a wolf and Julius is a lion'.
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.
    0.1::factC.
    %hop1
    0.7::factX:-xor(factB,factA).
    0.2::factY:-and(factB,factA).
    0.5::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-and(factX,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Winona is a wolf and Julius is a lion'.