There is almost no chance that Bernhard is a rhino. There is a very good chance that Winona is a cat. It is improbable that Brian is a swan. There is a better than even chance that if 'Brian is a swan' or 'Winona is a cat' or both then Jessica is a mouse. It is almost certain that if either 'Brian is a swan' or 'Winona is a cat' but not both then Sandra dropped the milk. There is almost no chance that if 'Brian is a swan and Winona is a cat' then Mary left the football.
It is highly likely that either 'Sandra dropped the milk' or 'Winona is a cat' but not both.
Chances are slight that either 'Sandra dropped the milk' or 'Winona is a cat' but not both.
It is highly likely that either 'Sandra dropped the milk' or 'Winona is a cat' 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
  0.02::factA.
  0.8::factB.
  0.1::factC.
  %hop1
  0.6::factX:-or(factC,factB).
  0.95::factY:-xor(factC,factB).
  0.02::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Sandra dropped the milk' or 'Winona is a cat' but not both.