context: It is highly likely that Mary dropped the milk. There is almost no chance that Julius is gray. It is almost certain that Lily is a lion. There is little chance that if either 'Mary dropped the milk' or 'Julius is gray' but not both then Sandra left the milk. There is a very good chance that if 'Mary dropped the milk' or 'Lily is a lion' or both then John moved to the office. It is improbable that if 'Mary dropped the milk and Lily is a lion' then Brian is yellow.
hypothesis: It is probable that 'Brian is yellow' or 'Julius is gray' or both.
valid_hypothesis: There is little chance that 'Brian is yellow' or 'Julius is gray' or both.
invalid_hypothesis: It is probable that 'Brian is yellow' or 'Julius is gray' 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
    0.9::factA.
    0.02::factB.
    0.95::factC.
    %hop1
    0.1::factX:-xor(factA,factB).
    0.8::factY:-or(factA,factC).
    0.1::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-or(factZ,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is yellow' or 'Julius is gray' or both.