context: There is almost no chance that Julius is gray. It is probably not the case that Gertrude is a sheep. It is highly unlikely that John went to the bedroom. There is little chance that if 'Julius is gray' or 'Gertrude is a sheep' or both then Sandra dropped the milk. It is improbable that if either 'Julius is gray' or 'Gertrude is a sheep' but not both then Daniel took the apple. It is probably not the case that if 'Gertrude is a sheep' or 'John went to the bedroom' or both then Greg is yellow.
hypothesis: Chances are about even that 'Julius is gray and Gertrude is a sheep'.
valid_hypothesis: It is impossible that 'Julius is gray and Gertrude is a sheep'.
invalid_hypothesis: Chances are about even that 'Julius is gray and Gertrude is a sheep'.
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
    0.02::factA.
    0.25::factB.
    0.05::factC.
    %hop1
    0.1::factX:-or(factA,factB).
    0.1::factY:-xor(factA,factB).
    0.25::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-and(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is gray and Gertrude is a sheep'.