There is a very good chance that John went to the garden. Chances are slight that Lily is a rhino. It is impossible that Bernhard is gray. It is highly unlikely that if 'Bernhard is gray and Lily is a rhino' then Winona is a mouse. It is certain that if either 'Lily is a rhino' or 'John went to the garden' but not both then Julius is white. There is little chance that if 'John went to the garden and Lily is a rhino' then Emily is a sheep.
It is impossible that either 'Winona is a mouse' or 'Emily is a sheep' but not both.
It is impossible that either 'Winona is a mouse' or 'Emily is a sheep' but not both.
There is a very good chance that either 'Winona is a mouse' or 'Emily is a sheep' 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
  0.8::factA.
  0.1::factB.
  0.0::factC.
  %hop1
  0.05::factX:-and(factC,factB).
  1.0::factY:-xor(factB,factA).
  0.1::factZ:-and(factA,factB).

  %hop2
  conclusion:-xor(factX,factZ).

  query(conclusion).
  
Either 'Winona is a mouse' or 'Emily is a sheep' but not both.