context: It is almost certain that Julius is a lion. It is likely that Jessica is a sheep. It is unlikely that Mary went to the kitchen. Chances are slight that if 'Jessica is a sheep and Mary went to the kitchen' then Bill left the football. It is highly unlikely that if 'Jessica is a sheep and Julius is a lion' then Lily is white. We doubt that if 'Mary went to the kitchen and Jessica is a sheep' then Brian is green.
hypothesis: It is unlikely that either 'Mary went to the kitchen' or 'Lily is white' but not both.
valid_hypothesis: It is unlikely that either 'Mary went to the kitchen' or 'Lily is white' but not both.
invalid_hypothesis: It is probably the case that either 'Mary went to the kitchen' or 'Lily is white' 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.
    0.7::factB.
    0.2::factC.
    %hop1
    0.1::factX:-and(factB,factC).
    0.05::factY:-and(factB,factA).
    0.2::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-xor(factC,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary went to the kitchen' or 'Lily is white' but not both.