It is probably the case that Gertrude is a mouse. There is little chance that Julius is a frog. It is highly unlikely that Jeff dropped the apple. It is probably the case that if either 'Julius is a frog' or 'Jeff dropped the apple' but not both then Emily is a wolf. There is little chance that if 'Jeff dropped the apple' or 'Gertrude is a mouse' or both then Bernhard is a swan. There is a very good chance that if 'Jeff dropped the apple' or 'Gertrude is a mouse' or both then Sandra left the milk.
It is highly unlikely that either 'Jeff dropped the apple' or 'Gertrude is a mouse' but not both.
It is probably the case that either 'Jeff dropped the apple' or 'Gertrude is a mouse' but not both.
It is highly unlikely that either 'Jeff dropped the apple' or 'Gertrude is a mouse' 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.
  0.05::factC.
  %hop1
  0.7::factX:-xor(factB,factC).
  0.1::factY:-or(factC,factA).
  0.8::factZ:-or(factC,factA).

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

  query(conclusion).
  
Either 'Jeff dropped the apple' or 'Gertrude is a mouse' but not both.