Chances are about even that Daniel put down the milk. We doubt that Mary moved to the garden. It is impossible that Jessica is a sheep. We believe that if 'Jessica is a sheep and Mary moved to the garden' then Antoine is hungry. It is probably not the case that if 'Jessica is a sheep and Daniel put down the milk' then Lily is white. It is unlikely that if either 'Mary moved to the garden' or 'Jessica is a sheep' but not both then Brian is a swan.
It is highly unlikely that either 'Brian is a swan' or 'Antoine is hungry' but not both.
It is highly unlikely that either 'Brian is a swan' or 'Antoine is hungry' but not both.
It is almost certain that either 'Brian is a swan' or 'Antoine is hungry' 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
  0.5::factA.
  0.2::factB.
  0.0::factC.
  %hop1
  0.75::factX:-and(factC,factB).
  0.25::factY:-and(factC,factA).
  0.2::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Brian is a swan' or 'Antoine is hungry' but not both.