We doubt that Julius is white. It is impossible that Bernhard is a lion. It is probable that Brian is gray. It is unlikely that if either 'Brian is gray' or 'Bernhard is a lion' but not both then Daniel dropped the milk. It is highly likely that if 'Bernhard is a lion and Julius is white' then Mary left the football. There is a very good chance that if 'Brian is gray and Bernhard is a lion' then Greg is a swan.
It is probably the case that 'Julius is white' or 'Daniel dropped the milk' or both.
It is probably not the case that 'Julius is white' or 'Daniel dropped the milk' or both.
It is probably the case that 'Julius is white' or 'Daniel 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
  0.2::factA.
  0.0::factB.
  0.7::factC.
  %hop1
  0.2::factX:-xor(factC,factB).
  0.9::factY:-and(factB,factA).
  0.8::factZ:-and(factC,factB).

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

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