We believe that Gertrude is a cat. It is highly likely that Brian is a swan. There is almost no chance that Bernhard is a rhino. It is improbable that if either 'Gertrude is a cat' or 'Bernhard is a rhino' but not both then Sandra left the milk. It is probably the case that if either 'Brian is a swan' or 'Gertrude is a cat' but not both then John went to the bedroom. There is little chance that if 'Gertrude is a cat and Brian is a swan' then Julius is gray.
It is almost certain that 'John went to the bedroom' or 'Brian is a swan' or both.
It is almost certain that 'John went to the bedroom' or 'Brian is a swan' or both.
Chances are slight that 'John went to the bedroom' or 'Brian is a swan' 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
  0.75::factA.
  0.9::factB.
  0.02::factC.
  %hop1
  0.1::factX:-xor(factA,factC).
  0.7::factY:-xor(factB,factA).
  0.1::factZ:-and(factA,factB).

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

  query(conclusion).
  
'John went to the bedroom' or 'Brian is a swan' or both.