We doubt that Gertrude is a sheep. We doubt that John went to the office. It is certain that Mary grabbed the apple. It is probably the case that if 'Mary grabbed the apple' or 'Gertrude is a sheep' or both then Greg is a swan. It is probably the case that if 'John went to the office and Mary grabbed the apple' then Bernhard is a frog. It is improbable that if either 'John went to the office' or 'Gertrude is a sheep' but not both then Julius is white.
It is highly likely that either 'Mary grabbed the apple' or 'Bernhard is a frog' but not both.
It is highly likely that either 'Mary grabbed the apple' or 'Bernhard is a frog' but not both.
It is impossible that either 'Mary grabbed the apple' or 'Bernhard is a frog' 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.
  0.2::factB.
  1.0::factC.
  %hop1
  0.7::factX:-or(factC,factA).
  0.7::factY:-and(factB,factC).
  0.1::factZ:-xor(factB,factA).

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

  query(conclusion).
  
Either 'Mary grabbed the apple' or 'Bernhard is a frog' but not both.