It is probable that Mary got the milk. We believe that John moved to the garden. There is almost no chance that Brian is white. We doubt that if 'Brian is white and Mary got the milk' then Jason is tired. There is little chance that if either 'Brian is white' or 'Mary got the milk' but not both then Gertrude is a wolf. It is impossible that if 'Brian is white and Mary got the milk' then Jessica is a mouse.
It is probably the case that either 'Jason is tired' or 'Mary got the milk' but not both.
It is probably the case that either 'Jason is tired' or 'Mary got the milk' but not both.
It is probably not the case that either 'Jason is tired' or 'Mary got 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
  0.7::factA.
  0.75::factB.
  0.02::factC.
  %hop1
  0.2::factX:-and(factC,factA).
  0.1::factY:-xor(factC,factA).
  0.0::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Jason is tired' or 'Mary got the milk' but not both.