We doubt that Gertrude is a sheep. It is probable that Bernhard is a lion. It is improbable that John put down the milk. It is likely that if 'Bernhard is a lion and Gertrude is a sheep' then Lily is gray. There is almost no chance that if 'Gertrude is a sheep' or 'Bernhard is a lion' or both then Mary took the football. It is probably the case that if either 'John put down the milk' or 'Gertrude is a sheep' but not both then Greg is a frog.
It is almost certain that either 'Mary took the football' or 'Gertrude is a sheep' but not both.
It is unlikely that either 'Mary took the football' or 'Gertrude is a sheep' but not both.
It is almost certain that either 'Mary took the football' or 'Gertrude is a sheep' 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
  0.2::factA.
  0.7::factB.
  0.1::factC.
  %hop1
  0.7::factX:-and(factB,factA).
  0.02::factY:-or(factA,factB).
  0.7::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Mary took the football' or 'Gertrude is a sheep' but not both.