It is impossible that Jessica is a mouse. It is highly likely that John grabbed the apple. It is probable that Brian is a frog. It is almost certain that if either 'Jessica is a mouse' or 'Brian is a frog' but not both then Daniel left the milk. It is probably not the case that if either 'Brian is a frog' or 'John grabbed the apple' but not both then Bernhard is green. It is probably the case that if either 'John grabbed the apple' or 'Jessica is a mouse' but not both then Gertrude is a sheep.
It is impossible that either 'Daniel left the milk' or 'Gertrude is a sheep' but not both.
Chances are about even that either 'Daniel left the milk' or 'Gertrude is a sheep' but not both.
It is impossible that either 'Daniel left the milk' or 'Gertrude 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
  0.0::factA.
  0.9::factB.
  0.7::factC.
  %hop1
  0.95::factX:-xor(factA,factC).
  0.25::factY:-xor(factC,factB).
  0.7::factZ:-xor(factB,factA).

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

  query(conclusion).
  
Either 'Daniel left the milk' or 'Gertrude is a sheep' but not both.