There is a very good chance that Lily is white. It is improbable that Mary dropped the milk. Chances are about even that Emily is a mouse. It is likely that if 'Mary dropped the milk and Lily is white' then Brian is yellow. It is improbable that if either 'Mary dropped the milk' or 'Emily is a mouse' but not both then Winona is a sheep. Chances are slight that if 'Emily is a mouse and Mary dropped the milk' then John got the apple.
It is almost certain that either 'Lily is white' or 'Emily is a mouse' but not both.
Chances are about even that either 'Lily is white' or 'Emily is a mouse' but not both.
It is almost certain that either 'Lily is white' or 'Emily is a mouse' 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
  0.8::factA.
  0.1::factB.
  0.5::factC.
  %hop1
  0.7::factX:-and(factB,factA).
  0.1::factY:-xor(factB,factC).
  0.1::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Lily is white' or 'Emily is a mouse' but not both.