context: We doubt that Gertrude is a cat. It is improbable that Julius is a swan. It is unlikely that Fred went to the garden. It is probably the case that if 'Julius is a swan' or 'Gertrude is a cat' or both then Lily is yellow. There is a better than even chance that if 'Julius is a swan and Gertrude is a cat' then Bernhard is gray. It is unlikely that if either 'Julius is a swan' or 'Fred went to the garden' but not both then Brian is green.
hypothesis: It is probably not the case that either 'Gertrude is a cat' or 'Fred went to the garden' but not both.
valid_hypothesis: It is probably not the case that either 'Gertrude is a cat' or 'Fred went to the garden' but not both.
invalid_hypothesis: It is certain that either 'Gertrude is a cat' or 'Fred went to the garden' but not 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
    0.2::factA.
    0.1::factB.
    0.2::factC.
    %hop1
    0.7::factX:-or(factB,factA).
    0.6::factY:-and(factB,factA).
    0.2::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-xor(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a cat' or 'Fred went to the garden' but not both.