We believe that Brian is yellow. There is almost no chance that Mary discarded the milk. It is almost certain that Lily is a lion. It is improbable that if 'Mary discarded the milk and Lily is a lion' then John went to the hallway. It is probable that if either 'Lily is a lion' or 'Mary discarded the milk' but not both then Bernhard is white. It is highly unlikely that if 'Brian is yellow and Mary discarded the milk' then Jeff dropped the apple.
It is almost certain that either 'Lily is a lion' or 'Mary discarded the milk' but not both.
It is almost certain that either 'Lily is a lion' or 'Mary discarded the milk' but not both.
There is little chance that either 'Lily is a lion' or 'Mary discarded the milk' but not both.

  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
  0.75::factA.
  0.02::factB.
  0.95::factC.
  %hop1
  0.1::factX:-and(factB,factC).
  0.7::factY:-xor(factC,factB).
  0.05::factZ:-and(factA,factB).

  %hop2
  conclusion:-xor(factC,factB).

  query(conclusion).
  
Either 'Lily is a lion' or 'Mary discarded the milk' but not both.