context: There is a very good chance that Gertrude is a sheep. We believe that Julius is a lion. It is probably not the case that Jeff put down the milk. There is little chance that if 'Jeff put down the milk' or 'Julius is a lion' or both then Emily is a wolf. It is impossible that if 'Julius is a lion' or 'Gertrude is a sheep' or both then Bernhard is a swan. It is probable that if either 'Julius is a lion' or 'Jeff put down the milk' but not both then Mary went to the hallway.
hypothesis: It is highly unlikely that either 'Mary went to the hallway' or 'Jeff put down the milk' but not both.
valid_hypothesis: There is a better than even chance that either 'Mary went to the hallway' or 'Jeff put down the milk' but not both.
invalid_hypothesis: It is highly unlikely that either 'Mary went to the hallway' or 'Jeff put down the milk' 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
    0.8::factA.
    0.75::factB.
    0.25::factC.
    %hop1
    0.1::factX:-or(factC,factB).
    0.0::factY:-or(factB,factA).
    0.7::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-xor(factZ,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Mary went to the hallway' or 'Jeff put down the milk' but not both.