It is improbable that Mary dropped the milk. It is improbable that Brian is a lion. There is a better than even chance that Bernhard is green. It is unlikely that if 'Bernhard is green and Brian is a lion' then John put down the apple. It is highly likely that if either 'Brian is a lion' or 'Mary dropped the milk' but not both then Julius is yellow. It is improbable that if 'Bernhard is green and Mary dropped the milk' then Lily is a swan.
Chances are about even that 'John put down the apple' or 'Lily is a swan' or both.
There is almost no chance that 'John put down the apple' or 'Lily is a swan' or both.
Chances are about even that 'John put down the apple' or 'Lily is a swan' 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
  0.1::factA.
  0.1::factB.
  0.6::factC.
  %hop1
  0.2::factX:-and(factC,factB).
  0.9::factY:-xor(factB,factA).
  0.1::factZ:-and(factC,factA).

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

  query(conclusion).
  
'John put down the apple' or 'Lily is a swan' or both.