It is unlikely that Sandra took the milk. It is likely that John went to the kitchen. It is highly likely that Brian is a swan. There is little chance that if either 'Brian is a swan' or 'John went to the kitchen' but not both then Mary left the football. There is a very good chance that if either 'Brian is a swan' or 'John went to the kitchen' but not both then Emily is a mouse. Chances are about even that if 'John went to the kitchen' or 'Brian is a swan' or both then Julius is gray.
Chances are about even that either 'Emily is a mouse' or 'Julius is gray' but not both.
Chances are about even that either 'Emily is a mouse' or 'Julius is gray' but not both.
It is certain that either 'Emily is a mouse' or 'Julius is gray' 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
  0.2::factA.
  0.7::factB.
  0.9::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.8::factY:-xor(factC,factB).
  0.5::factZ:-or(factB,factC).

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

  query(conclusion).
  
Either 'Emily is a mouse' or 'Julius is gray' but not both.