It is probably not the case that Julius is a swan. There is a better than even chance that Sandra left the milk. It is probably the case that Lily is a frog. It is probably not the case that if either 'Sandra left the milk' or 'Lily is a frog' but not both then Brian is a rhino. It is highly likely that if 'Sandra left the milk and Lily is a frog' then John went to the garden. We doubt that if 'Sandra left the milk' or 'Julius is a swan' or both then Bernhard is yellow.
It is impossible that either 'Bernhard is yellow' or 'Lily is a frog' but not both.
There is a better than even chance that either 'Bernhard is yellow' or 'Lily is a frog' but not both.
It is impossible that either 'Bernhard is yellow' or 'Lily is a frog' 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
  0.25::factA.
  0.6::factB.
  0.7::factC.
  %hop1
  0.25::factX:-xor(factB,factC).
  0.9::factY:-and(factB,factC).
  0.2::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Bernhard is yellow' or 'Lily is a frog' but not both.