context: It is almost certain that Lily is a swan. It is highly unlikely that Daniel grabbed the milk. Chances are slight that Julius is a rhino. It is unlikely that if either 'Daniel grabbed the milk' or 'Lily is a swan' but not both then Jeff moved to the garden. It is impossible that if either 'Julius is a rhino' or 'Daniel grabbed the milk' but not both then Mary went to the bedroom. Chances are about even that if 'Julius is a rhino and Lily is a swan' then Bernhard is white.
hypothesis: It is highly unlikely that either 'Daniel grabbed the milk' or 'Mary went to the bedroom' but not both.
valid_hypothesis: It is highly unlikely that either 'Daniel grabbed the milk' or 'Mary went to the bedroom' but not both.
invalid_hypothesis: It is highly likely that either 'Daniel grabbed the milk' or 'Mary 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
    0.95::factA.
    0.05::factB.
    0.1::factC.
    %hop1
    0.2::factX:-xor(factB,factA).
    0.0::factY:-xor(factC,factB).
    0.5::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Daniel grabbed the milk' or 'Mary went to the bedroom' but not both.