It is certain that Julius is a swan. Chances are slight that John grabbed the milk. It is impossible that Bernhard is a lion. It is unlikely that if either 'Bernhard is a lion' or 'John grabbed the milk' but not both then Winona is a cat. It is highly likely that if 'John grabbed the milk and Bernhard is a lion' then Mary went to the bedroom. It is improbable that if either 'Bernhard is a lion' or 'Julius is a swan' but not both then Brian is a rhino.
It is certain that 'Winona is a cat and Mary went to the bedroom'.
It is impossible that 'Winona is a cat and Mary went to the bedroom'.
It is certain that 'Winona is a cat and Mary went to the bedroom'.

  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
  1.0::factA.
  0.1::factB.
  0.0::factC.
  %hop1
  0.2::factX:-xor(factC,factB).
  0.9::factY:-and(factB,factC).
  0.1::factZ:-xor(factC,factA).

  %hop2
  conclusion:-and(factX,factY).

  query(conclusion).
  
'Winona is a cat and Mary went to the bedroom'.