It is highly likely that Sandra took the milk. It is highly unlikely that Mary is in the school. There is little chance that Winona is a mouse. Chances are about even that if 'Winona is a mouse and Sandra took the milk' then Julius is white. It is probably the case that if 'Winona is a mouse' or 'Mary is in the school' or both then Bernhard is green. It is highly unlikely that if either 'Mary is in the school' or 'Winona is a mouse' but not both then John dropped the apple.
There is a very good chance that either 'Sandra took the milk' or 'Bernhard is green' but not both.
There is a very good chance that either 'Sandra took the milk' or 'Bernhard is green' but not both.
It is improbable that either 'Sandra took the milk' or 'Bernhard is green' 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.
  0.05::factB.
  0.1::factC.
  %hop1
  0.5::factX:-and(factC,factA).
  0.7::factY:-or(factC,factB).
  0.05::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Sandra took the milk' or 'Bernhard is green' but not both.