It is probably the case that Winona is a wolf. It is impossible that Mary went to the hallway. There is a very good chance that Greg is gray. Chances are about even that if 'Greg is gray and Winona is a wolf' then John got the apple. It is probably the case that if either 'Winona is a wolf' or 'Greg is gray' but not both then Sandra left the football. It is probable that if 'Greg is gray' or 'Mary went to the hallway' or both then Gertrude is a sheep.
It is likely that either 'Winona is a wolf' or 'Mary went to the hallway' but not both.
It is likely that either 'Winona is a wolf' or 'Mary went to the hallway' but not both.
It is highly unlikely that either 'Winona is a wolf' or 'Mary went to the hallway' 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.
  0.0::factB.
  0.8::factC.
  %hop1
  0.5::factX:-and(factC,factA).
  0.7::factY:-xor(factA,factC).
  0.7::factZ:-or(factC,factB).

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

  query(conclusion).
  
Either 'Winona is a wolf' or 'Mary went to the hallway' but not both.