There is almost no chance that Jessica is a cat. Chances are about even that Mary left the football. It is improbable that Julius is a frog. It is improbable that if either 'Jessica is a cat' or 'Julius is a frog' but not both then Sandra dropped the milk. Chances are about even that if 'Julius is a frog and Jessica is a cat' then Brian is a swan. It is impossible that if either 'Jessica is a cat' or 'Mary left the football' but not both then Bernhard is white.
There is almost no chance that 'Brian is a swan' or 'Mary left the football' or both.
Chances are about even that 'Brian is a swan' or 'Mary left the football' or both.
There is almost no chance that 'Brian is a swan' or 'Mary left the football' or 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
  0.02::factA.
  0.5::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factA,factC).
  0.5::factY:-and(factC,factA).
  0.0::factZ:-xor(factA,factB).

  %hop2
  conclusion:-or(factY,factB).

  query(conclusion).
  
'Brian is a swan' or 'Mary left the football' or both.