context: It is certain that John went to the kitchen. It is probably the case that Lily is white. Chances are about even that Brian is a lion. It is improbable that if either 'Brian is a lion' or 'John went to the kitchen' but not both then Julius is green. It is highly likely that if 'Lily is white' or 'Brian is a lion' or both then Greg is yellow. It is probable that if 'Brian is a lion and Lily is white' then Mary put down the milk.
hypothesis: It is impossible that 'Brian is a lion and Julius is green'.
valid_hypothesis: It is impossible that 'Brian is a lion and Julius is green'.
invalid_hypothesis: There is a better than even chance that 'Brian is a lion and Julius is green'.
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
    1.0::factA.
    0.7::factB.
    0.5::factC.
    %hop1
    0.1::factX:-xor(factC,factA).
    0.9::factY:-or(factB,factC).
    0.7::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-and(factC,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a lion and Julius is green'.