It is impossible that Gertrude is a sheep. It is unlikely that Bernhard is green. It is likely that Mary went to the hallway. Chances are about even that if 'Mary went to the hallway and Bernhard is green' then Julius is gray. There is almost no chance that if 'Gertrude is a sheep' or 'Mary went to the hallway' or both then Sandra dropped the milk. It is certain that if 'Gertrude is a sheep' or 'Mary went to the hallway' or both then Brian is a swan.
It is likely that 'Gertrude is a sheep' or 'Mary went to the hallway' or both.
It is likely that 'Gertrude is a sheep' or 'Mary went to the hallway' or both.
We doubt that 'Gertrude is a sheep' or 'Mary 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
  0.0::factA.
  0.2::factB.
  0.7::factC.
  %hop1
  0.5::factX:-and(factC,factB).
  0.02::factY:-or(factA,factC).
  1.0::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Gertrude is a sheep' or 'Mary went to the hallway' or both.