We doubt that John left the football. It is certain that Greg is a swan. Chances are about even that Antoine is hungry. It is almost certain that if either 'John left the football' or 'Greg is a swan' but not both then Julius is white. It is unlikely that if either 'Antoine is hungry' or 'John left the football' but not both then Brian is white. It is unlikely that if either 'Antoine is hungry' or 'John left the football' but not both then Mary put down the apple.
Chances are about even that 'Antoine is hungry' or 'Brian is white' or both.
Chances are about even that 'Antoine is hungry' or 'Brian is white' or both.
It is highly unlikely that 'Antoine is hungry' or 'Brian is white' 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.
  1.0::factB.
  0.5::factC.
  %hop1
  0.95::factX:-xor(factA,factB).
  0.2::factY:-xor(factC,factA).
  0.2::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Antoine is hungry' or 'Brian is white' or both.