It is certain that Julius is white. Chances are about even that Bernhard is green. It is highly likely that Lily is a swan. It is highly unlikely that if 'Lily is a swan and Bernhard is green' then John moved to the office. There is a very good chance that if 'Lily is a swan and Julius is white' then Mary dropped the apple. It is unlikely that if 'Bernhard is green' or 'Lily is a swan' or both then Sandra left the football.
We doubt that 'Lily is a swan' or 'Bernhard is green' or both.
It is almost certain that 'Lily is a swan' or 'Bernhard is green' or both.
We doubt that 'Lily is a swan' or 'Bernhard is green' 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
  1.0::factA.
  0.5::factB.
  0.9::factC.
  %hop1
  0.05::factX:-and(factC,factB).
  0.8::factY:-and(factC,factA).
  0.2::factZ:-or(factB,factC).

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

  query(conclusion).
  
'Lily is a swan' or 'Bernhard is green' or both.