It is almost certain that Lily is a frog. We believe that Bernhard is white. Chances are slight that Gertrude is a cat. It is probably the case that if 'Bernhard is white and Gertrude is a cat' then Brian is yellow. It is probably the case that if 'Lily is a frog and Bernhard is white' then Mary left the milk. There is little chance that if 'Lily is a frog' or 'Bernhard is white' or both then John went to the hallway.
We doubt that 'Gertrude is a cat' or 'John went to the hallway' or both.
We doubt that 'Gertrude is a cat' or 'John went to the hallway' or both.
We believe that 'Gertrude is a cat' or 'John went to the hallway' 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
  0.95::factA.
  0.75::factB.
  0.1::factC.
  %hop1
  0.7::factX:-and(factB,factC).
  0.7::factY:-and(factA,factB).
  0.1::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Gertrude is a cat' or 'John went to the hallway' or both.