It is unlikely that Julius is a frog. Chances are about even that Brian is gray. We doubt that Lily is yellow. It is highly likely that if 'Julius is a frog' or 'Brian is gray' or both then Mary went to the kitchen. It is certain that if 'Lily is yellow and Julius is a frog' then Winona is a sheep. Chances are about even that if 'Lily is yellow and Julius is a frog' then John left the milk.
It is impossible that 'Mary went to the kitchen' or 'Julius is a frog' or both.
There is a better than even chance that 'Mary went to the kitchen' or 'Julius is a frog' or both.
It is impossible that 'Mary went to the kitchen' or 'Julius is a frog' 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
  0.2::factA.
  0.5::factB.
  0.2::factC.
  %hop1
  0.9::factX:-or(factA,factB).
  1.0::factY:-and(factC,factA).
  0.5::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Mary went to the kitchen' or 'Julius is a frog' or both.