It is probably not the case that Bernhard is yellow. We doubt that Mary went to the bedroom. There is little chance that Winona is a sheep. We doubt that if 'Mary went to the bedroom' or 'Bernhard is yellow' or both then Brian is a swan. It is likely that if 'Mary went to the bedroom and Winona is a sheep' then John moved to the garden. It is likely that if 'Bernhard is yellow' or 'Mary went to the bedroom' or both then Lily is a lion.
Chances are slight that either 'Winona is a sheep' or 'John moved to the garden' but not both.
Chances are slight that either 'Winona is a sheep' or 'John moved to the garden' but not both.
There is a very good chance that either 'Winona is a sheep' or 'John moved to the garden' 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.
  0.2::factB.
  0.1::factC.
  %hop1
  0.2::factX:-or(factB,factA).
  0.7::factY:-and(factB,factC).
  0.7::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Winona is a sheep' or 'John moved to the garden' but not both.