context: It is highly likely that Mary dropped the milk. There is a better than even chance that Sandra left the football. It is probably the case that Gertrude is a cat.
hypothesis: Chances are about even that either 'Gertrude is a cat' or 'Sandra left the football' but not both.
valid_hypothesis: Chances are about even that either 'Gertrude is a cat' or 'Sandra left the football' but not both.
invalid_hypothesis: It is highly unlikely that either 'Gertrude is a cat' or 'Sandra left 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.
    0.6::factB.
    0.7::factC.
    
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Gertrude is a cat' or 'Sandra left the football' but not both.