It is impossible that Julius is yellow. It is almost certain that John went to the kitchen. It is probable that Gertrude is a mouse. It is probably not the case that if 'Gertrude is a mouse and Julius is yellow' then Bernhard is a swan. It is probably not the case that if 'Julius is yellow and John went to the kitchen' then Jessica is a cat. Chances are about even that if 'John went to the kitchen' or 'Julius is yellow' or both then Yann is hungry.
It is likely that either 'Gertrude is a mouse' or 'Bernhard is a swan' but not both.
It is likely that either 'Gertrude is a mouse' or 'Bernhard is a swan' but not both.
It is probably not the case that either 'Gertrude is a mouse' or 'Bernhard is a swan' 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
  0.0::factA.
  0.95::factB.
  0.7::factC.
  %hop1
  0.25::factX:-and(factC,factA).
  0.25::factY:-and(factA,factB).
  0.5::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Gertrude is a mouse' or 'Bernhard is a swan' but not both.