context: We doubt that Bernhard is white. It is improbable that Mary went to the bedroom. Chances are about even that Brian is a rhino. It is impossible that if 'Mary went to the bedroom' or 'Brian is a rhino' or both then Lily is gray. It is likely that if either 'Brian is a rhino' or 'Mary went to the bedroom' but not both then Greg is a frog. It is highly likely that if 'Brian is a rhino and Mary went to the bedroom' then John got the milk.
hypothesis: It is probably not the case that either 'Mary went to the bedroom' or 'Bernhard is white' but not both.
valid_hypothesis: It is probably not the case that either 'Mary went to the bedroom' or 'Bernhard is white' but not both.
invalid_hypothesis: It is likely that either 'Mary went to the bedroom' or 'Bernhard 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
    0.2::factA.
    0.1::factB.
    0.5::factC.
    %hop1
    0.0::factX:-or(factB,factC).
    0.7::factY:-xor(factC,factB).
    0.9::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary went to the bedroom' or 'Bernhard is white' but not both.