context: We doubt that Brian is green. It is unlikely that Gertrude is a cat. It is highly likely that Emily is a mouse. We believe that if 'Emily is a mouse and Gertrude is a cat' then John took the football. It is highly likely that if 'Brian is green and Gertrude is a cat' then Greg is a swan. It is certain that if either 'Gertrude is a cat' or 'Emily is a mouse' but not both then Fred went to the office.
hypothesis: There is almost no chance that either 'Gertrude is a cat' or 'Emily is a mouse' but not both.
valid_hypothesis: We believe that either 'Gertrude is a cat' or 'Emily is a mouse' but not both.
invalid_hypothesis: There is almost no chance that either 'Gertrude is a cat' or 'Emily is a mouse' 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.
    0.2::factB.
    0.9::factC.
    %hop1
    0.75::factX:-and(factC,factB).
    0.9::factY:-and(factA,factB).
    1.0::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-xor(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a cat' or 'Emily is a mouse' but not both.