context: It is highly likely that Julius is a rhino. It is almost certain that Gertrude is a mouse. It is highly unlikely that Bernhard is a swan. Chances are about even that if 'Julius is a rhino and Bernhard is a swan' then Lily is gray. There is a better than even chance that if 'Julius is a rhino' or 'Gertrude is a mouse' or both then Sandra got the football. There is a better than even chance that if 'Bernhard is a swan' or 'Gertrude is a mouse' or both then John went to the kitchen.
hypothesis: It is highly unlikely that either 'Gertrude is a mouse' or 'Sandra got the football' but not both.
valid_hypothesis: Chances are about even that either 'Gertrude is a mouse' or 'Sandra got the football' but not both.
invalid_hypothesis: It is highly unlikely that either 'Gertrude is a mouse' or 'Sandra got the football' 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
    0.9::factA.
    0.95::factB.
    0.05::factC.
    %hop1
    0.5::factX:-and(factA,factC).
    0.6::factY:-or(factA,factB).
    0.6::factZ:-or(factC,factB).
  
    %hop2
    conclusion:-xor(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a mouse' or 'Sandra got the football' but not both.