context: It is improbable that Julius is a swan. It is highly unlikely that Sandra left the football. Chances are slight that John put down the apple. It is impossible that if either 'Sandra left the football' or 'Julius is a swan' but not both then Winona is a mouse. It is almost certain that if 'Sandra left the football and Julius is a swan' then Mary went to the kitchen. Chances are about even that if either 'Sandra left the football' or 'Julius is a swan' but not both then Lily is a swan.
hypothesis: Chances are about even that either 'Mary went to the kitchen' or 'Winona is a mouse' but not both.
valid_hypothesis: It is impossible that either 'Mary went to the kitchen' or 'Winona is a mouse' but not both.
invalid_hypothesis: Chances are about even that either 'Mary went to the kitchen' or 'Winona 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
    0.1::factA.
    0.05::factB.
    0.1::factC.
    %hop1
    0.0::factX:-xor(factB,factA).
    0.95::factY:-and(factB,factA).
    0.5::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-xor(factY,factX).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary went to the kitchen' or 'Winona is a mouse' but not both.