context: Chances are about even that Greg is white. We doubt that Gertrude is a sheep. It is highly unlikely that John went to the office. It is certain that if 'Gertrude is a sheep and John went to the office' then Bernhard is white. It is probably the case that if 'Gertrude is a sheep and Greg is white' then Mary put down the milk. It is almost certain that if either 'Gertrude is a sheep' or 'Greg is white' but not both then Julius is gray.
hypothesis: Chances are about even that 'John went to the office' or 'Julius is gray' or both.
valid_hypothesis: Chances are about even that 'John went to the office' or 'Julius is gray' or both.
invalid_hypothesis: There is almost no chance that 'John went to the office' 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
    0.5::factA.
    0.2::factB.
    0.05::factC.
    %hop1
    1.0::factX:-and(factB,factC).
    0.7::factY:-and(factB,factA).
    0.95::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-or(factC,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'John went to the office' or 'Julius is gray' or both.