It is impossible that Gertrude is a sheep. It is probable that Mary got the milk. It is highly likely that Brian is a rhino. Chances are slight that if either 'Gertrude is a sheep' or 'Mary got the milk' but not both then Bernhard is green. It is almost certain that if either 'Mary got the milk' or 'Brian is a rhino' but not both then Julius is gray. It is certain that if 'Mary got the milk and Brian is a rhino' then John went to the bedroom.
It is improbable that 'Mary got the milk and Brian is a rhino'.
There is a better than even chance that 'Mary got the milk and Brian is a rhino'.
It is improbable that 'Mary got the milk and Brian is a rhino'.

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

  %hop2
  conclusion:-and(factB,factC).

  query(conclusion).
  
'Mary got the milk and Brian is a rhino'.