It is highly likely that Gertrude is a sheep. There is almost no chance that Jessica is a cat. It is probably not the case that Bill went to the bedroom. There is almost no chance that if 'Bill went to the bedroom' or 'Gertrude is a sheep' or both then Bernhard is gray. We doubt that if either 'Bill went to the bedroom' or 'Jessica is a cat' but not both then Greg is yellow. It is improbable that if either 'Bill went to the bedroom' or 'Gertrude is a sheep' but not both then Sandra took the milk.
It is almost certain that 'Bill went to the bedroom' or 'Gertrude is a sheep' or both.
It is almost certain that 'Bill went to the bedroom' or 'Gertrude is a sheep' or both.
We doubt that 'Bill went to the bedroom' or 'Gertrude is a sheep' 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
  0.9::factA.
  0.02::factB.
  0.25::factC.
  %hop1
  0.02::factX:-or(factC,factA).
  0.2::factY:-xor(factC,factB).
  0.1::factZ:-xor(factC,factA).

  %hop2
  conclusion:-or(factC,factA).

  query(conclusion).
  
'Bill went to the bedroom' or 'Gertrude is a sheep' or both.