It is improbable that Daniel took the apple. It is probably not the case that John moved to the office. We doubt that Mary went to the office. There is almost no chance that if 'Mary went to the office and John moved to the office' then Brian is yellow. It is probable that if 'Mary went to the office' or 'John moved to the office' or both then Gertrude is a mouse. We doubt that if either 'Mary went to the office' or 'Daniel took the apple' but not both then Bernhard is a frog.
It is almost certain that either 'Brian is yellow' or 'Mary went to the office' but not both.
It is unlikely that either 'Brian is yellow' or 'Mary went to the office' but not both.
It is almost certain that either 'Brian is yellow' or 'Mary went to the office' 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
  0.1::factA.
  0.25::factB.
  0.2::factC.
  %hop1
  0.02::factX:-and(factC,factB).
  0.7::factY:-or(factC,factB).
  0.2::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Brian is yellow' or 'Mary went to the office' but not both.