It is highly likely that Lily is a lion. There is almost no chance that Brian is green. It is certain that Mary left the football. It is probably not the case that if 'Mary left the football' or 'Lily is a lion' or both then Sandra took the milk. It is unlikely that if 'Brian is green' or 'Mary left the football' or both then John went to the garden. It is improbable that if 'Mary left the football and Lily is a lion' then Julius is a rhino.
There is almost no chance that either 'Lily is a lion' or 'Brian is green' but not both.
It is highly likely that either 'Lily is a lion' or 'Brian is green' but not both.
There is almost no chance that either 'Lily is a lion' or 'Brian is green' 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
  0.9::factA.
  0.02::factB.
  1.0::factC.
  %hop1
  0.25::factX:-or(factC,factA).
  0.2::factY:-or(factB,factC).
  0.1::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Lily is a lion' or 'Brian is green' but not both.