We believe that Mary left the apple. Chances are slight that Bernhard is a rhino. It is highly likely that Emily is a wolf. It is almost certain that if 'Emily is a wolf' or 'Bernhard is a rhino' or both then Lily is white. It is highly unlikely that if 'Bernhard is a rhino and Emily is a wolf' then Brian is a swan. It is impossible that if either 'Bernhard is a rhino' or 'Emily is a wolf' but not both then John went to the office.
It is probably not the case that either 'Emily is a wolf' or 'Mary left the apple' but not both.
It is probably not the case that either 'Emily is a wolf' or 'Mary left the apple' but not both.
It is certain that either 'Emily is a wolf' or 'Mary left the apple' 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
  0.75::factA.
  0.1::factB.
  0.9::factC.
  %hop1
  0.95::factX:-or(factC,factB).
  0.05::factY:-and(factB,factC).
  0.0::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Emily is a wolf' or 'Mary left the apple' but not both.