context: It is certain that Julius is a frog. It is probably the case that Gertrude is a sheep. It is almost certain that Greg is a swan. It is probable that if either 'Greg is a swan' or 'Gertrude is a sheep' but not both then Bernhard is gray. There is little chance that if 'Greg is a swan and Julius is a frog' then Mary went to the office. It is highly likely that if 'Greg is a swan and Julius is a frog' then Brian is white.
hypothesis: It is unlikely that 'Julius is a frog' or 'Gertrude is a sheep' or both.
valid_hypothesis: It is certain that 'Julius is a frog' or 'Gertrude is a sheep' or both.
invalid_hypothesis: It is unlikely that 'Julius is a frog' or 'Gertrude is a sheep' 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
    1.0::factA.
    0.7::factB.
    0.95::factC.
    %hop1
    0.7::factX:-xor(factC,factB).
    0.1::factY:-and(factC,factA).
    0.9::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-or(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a frog' or 'Gertrude is a sheep' or both.