It is probably the case that Winona is a wolf. There is little chance that Bernhard is a frog. It is almost certain that Julius is a swan. It is probably not the case that if 'Winona is a wolf and Bernhard is a frog' then Greg is a swan. It is probable that if 'Bernhard is a frog and Julius is a swan' then Fred left the apple. It is certain that if 'Bernhard is a frog' or 'Winona is a wolf' or both then Mary went to the bedroom.
It is probably not the case that either 'Winona is a wolf' or 'Fred left the apple' but not both.
It is probably the case that either 'Winona is a wolf' or 'Fred left the apple' but not both.
It is probably not the case that either 'Winona is a wolf' or 'Fred 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
  0.7::factA.
  0.1::factB.
  0.95::factC.
  %hop1
  0.25::factX:-and(factA,factB).
  0.7::factY:-and(factB,factC).
  1.0::factZ:-or(factB,factA).

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

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