context: There is a better than even chance that Bernhard is green. We believe that Mary went to the kitchen. It is probable that Lily is a swan. We believe that if 'Mary went to the kitchen' or 'Lily is a swan' or both then Brian is a lion. There is little chance that if either 'Lily is a swan' or 'Bernhard is green' but not both then John took the football. There is a better than even chance that if 'Bernhard is green' or 'Mary went to the kitchen' or both then Jessica is a mouse.
hypothesis: It is impossible that either 'Mary went to the kitchen' or 'Lily is a swan' but not both.
valid_hypothesis: Chances are about even that either 'Mary went to the kitchen' or 'Lily is a swan' but not both.
invalid_hypothesis: It is impossible that either 'Mary went to the kitchen' or 'Lily is a swan' 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
    0.6::factA.
    0.75::factB.
    0.7::factC.
    %hop1
    0.75::factX:-or(factB,factC).
    0.1::factY:-xor(factC,factA).
    0.6::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-xor(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary went to the kitchen' or 'Lily is a swan' but not both.