It is likely that Bernhard is white. It is probable that Lily is white. There is almost no chance that John put down the milk. We doubt that if either 'John put down the milk' or 'Lily is white' but not both then Daniel got the football. It is certain that if 'Bernhard is white' or 'Lily is white' or both then Julius is a lion. It is probably not the case that if 'Bernhard is white' or 'John put down the milk' or both then Mary went to the garden.
We believe that 'Bernhard is white' or 'Daniel got the football' or both.
We believe that 'Bernhard is white' or 'Daniel got the football' or both.
It is highly unlikely that 'Bernhard is white' or 'Daniel got the football' 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.
  0.7::factB.
  0.02::factC.
  %hop1
  0.2::factX:-xor(factC,factB).
  1.0::factY:-or(factA,factB).
  0.25::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Bernhard is white' or 'Daniel got the football' or both.