context: It is highly likely that Brian is a lion. It is probable that John took the apple. We doubt that Emily is a wolf. It is unlikely that if 'Brian is a lion and Emily is a wolf' then Jessica is a cat. There is almost no chance that if 'John took the apple' or 'Brian is a lion' or both then Lily is a swan. Chances are about even that if 'Brian is a lion and John took the apple' then Jeff went to the bedroom.
hypothesis: It is highly likely that either 'Lily is a swan' or 'Jeff went to the bedroom' but not both.
valid_hypothesis: It is probably not the case that either 'Lily is a swan' or 'Jeff went to the bedroom' but not both.
invalid_hypothesis: It is highly likely that either 'Lily is a swan' or 'Jeff went to the bedroom' 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.
    0.7::factB.
    0.2::factC.
    %hop1
    0.2::factX:-and(factA,factC).
    0.02::factY:-or(factB,factA).
    0.5::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-xor(factY,factZ).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a swan' or 'Jeff went to the bedroom' but not both.