context: It is almost certain that Greg is a swan. It is probably not the case that Julius is yellow. There is little chance that Gertrude is a mouse. There is a better than even chance that if 'Julius is yellow and Gertrude is a mouse' then Brian is a lion. It is impossible that if either 'Greg is a swan' or 'Julius is yellow' but not both then Bernhard is gray. There is a better than even chance that if 'Julius is yellow and Greg is a swan' then Mary grabbed the milk.
hypothesis: It is improbable that either 'Gertrude is a mouse' or 'Bernhard is gray' but not both.
valid_hypothesis: It is improbable that either 'Gertrude is a mouse' or 'Bernhard is gray' but not both.
invalid_hypothesis: It is highly likely that either 'Gertrude is a mouse' or 'Bernhard is gray' 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
    0.95::factA.
    0.25::factB.
    0.1::factC.
    %hop1
    0.6::factX:-and(factB,factC).
    0.0::factY:-xor(factA,factB).
    0.6::factZ:-and(factB,factA).
  
    %hop2
    conclusion:-xor(factC,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a mouse' or 'Bernhard is gray' but not both.