There is a better than even chance that Lily is a swan. It is impossible that Julius is a frog. We believe that Mary put down the apple. Chances are slight that if 'Julius is a frog and Mary put down the apple' then Sandra got the football. There is a better than even chance that if either 'Mary put down the apple' or 'Lily is a swan' but not both then Greg is a rhino. It is probably not the case that if 'Mary put down the apple and Julius is a frog' then Bernhard is white.
It is almost certain that either 'Mary put down the apple' or 'Lily is a swan' but not both.
Chances are about even that either 'Mary put down the apple' or 'Lily is a swan' but not both.
It is almost certain that either 'Mary put down the apple' or 'Lily is a swan' 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
  0.6::factA.
  0.0::factB.
  0.75::factC.
  %hop1
  0.1::factX:-and(factB,factC).
  0.6::factY:-xor(factC,factA).
  0.25::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Mary put down the apple' or 'Lily is a swan' but not both.