It is probably not the case that Brian is a frog. It is probably not the case that Jeff put down the milk. It is certain that Bernhard is a rhino. It is probably not the case that if 'Brian is a frog' or 'Jeff put down the milk' or both then Jessica is a cat. It is impossible that if either 'Bernhard is a rhino' or 'Brian is a frog' but not both then Julius is yellow. We doubt that if 'Brian is a frog' or 'Jeff put down the milk' or both then Mary went to the kitchen.
It is impossible that either 'Mary went to the kitchen' or 'Bernhard is a rhino' but not both.
It is highly likely that either 'Mary went to the kitchen' or 'Bernhard is a rhino' but not both.
It is impossible that either 'Mary went to the kitchen' or 'Bernhard is a rhino' 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
  0.25::factA.
  0.25::factB.
  1.0::factC.
  %hop1
  0.25::factX:-or(factA,factB).
  0.0::factY:-xor(factC,factA).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Mary went to the kitchen' or 'Bernhard is a rhino' but not both.