It is highly likely that Mary grabbed the milk. It is almost certain that Sandra left the football. There is a very good chance that Julius is white. It is probably not the case that if 'Julius is white and Mary grabbed the milk' then Gertrude is a mouse. It is unlikely that if 'Julius is white and Sandra left the football' then John moved to the garden. We believe that if 'Mary grabbed the milk and Sandra left the football' then Lily is green.
There is a very good chance that either 'Mary grabbed the milk' or 'John moved to the garden' but not both.
There is a very good chance that either 'Mary grabbed the milk' or 'John moved to the garden' but not both.
We doubt that either 'Mary grabbed the milk' 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
  0.9::factA.
  0.95::factB.
  0.8::factC.
  %hop1
  0.25::factX:-and(factC,factA).
  0.2::factY:-and(factC,factB).
  0.75::factZ:-and(factA,factB).

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

  query(conclusion).
  
Either 'Mary grabbed the milk' or 'John moved to the garden' but not both.