context: It is highly likely that Brian is a rhino. Chances are about even that Gertrude is a mouse. It is unlikely that Julius is gray. It is probably the case that if 'Gertrude is a mouse' or 'Julius is gray' or both then Greg is white. It is highly unlikely that if either 'Julius is gray' or 'Brian is a rhino' but not both then Mary went to the office. It is almost certain that if 'Julius is gray' or 'Brian is a rhino' or both then Daniel dropped the milk.
hypothesis: There is a better than even chance that 'Julius is gray' or 'Gertrude is a mouse' or both.
valid_hypothesis: There is a better than even chance that 'Julius is gray' or 'Gertrude is a mouse' or both.
invalid_hypothesis: Chances are slight that 'Julius is gray' or 'Gertrude is a mouse' 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.
    0.5::factB.
    0.2::factC.
    %hop1
    0.7::factX:-or(factB,factC).
    0.05::factY:-xor(factC,factA).
    0.95::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-or(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is gray' or 'Gertrude is a mouse' or both.