It is probably the case that Julius is white. It is certain that Fred dropped the milk. It is highly unlikely that Bernhard is gray. There is a better than even chance that if 'Fred dropped the milk and Julius is white' then Mary went to the garden. There is little chance that if either 'Bernhard is gray' or 'Fred dropped the milk' but not both then Lily is a rhino. There is little chance that if either 'Fred dropped the milk' or 'Bernhard is gray' but not both then Brian is a lion.
There is almost no chance that 'Julius is white' or 'Fred dropped the milk' or both.
It is certain that 'Julius is white' or 'Fred dropped the milk' or both.
There is almost no chance that 'Julius is white' or 'Fred dropped the milk' 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
  0.7::factA.
  1.0::factB.
  0.05::factC.
  %hop1
  0.6::factX:-and(factB,factA).
  0.1::factY:-xor(factC,factB).
  0.1::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Julius is white' or 'Fred dropped the milk' or both.