We believe that Lily is a rhino. Chances are about even that Mary left the football. It is certain that Julius is white. There is little chance that if 'Julius is white' or 'Mary left the football' or both then Bernhard is a frog. We doubt that if either 'Julius is white' or 'Mary left the football' but not both then John went to the kitchen. We believe that if 'Lily is a rhino and Mary left the football' then Brian is green.
It is certain that 'Julius is white' or 'John went to the kitchen' or both.
It is certain that 'Julius is white' or 'John went to the kitchen' or both.
It is probably not the case that 'Julius is white' or 'John went to the kitchen' 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
  0.75::factA.
  0.5::factB.
  1.0::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.2::factY:-xor(factC,factB).
  0.75::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Julius is white' or 'John went to the kitchen' or both.