There is a very good chance that Mary went to the bedroom. There is a very good chance that Bernhard is a swan. It is improbable that Antoine is bored. There is a better than even chance that if either 'Mary went to the bedroom' or 'Antoine is bored' but not both then Lily is a frog. It is probable that if 'Mary went to the bedroom' or 'Bernhard is a swan' or both then Bill moved to the office. We doubt that if 'Antoine is bored and Bernhard is a swan' then John dropped the apple.
It is almost certain that 'Bernhard is a swan' or 'Mary went to the bedroom' or both.
It is almost certain that 'Bernhard is a swan' or 'Mary went to the bedroom' or both.
There is almost no chance that 'Bernhard is a swan' or 'Mary went to the bedroom' 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
  0.8::factA.
  0.8::factB.
  0.1::factC.
  %hop1
  0.6::factX:-xor(factA,factC).
  0.7::factY:-or(factA,factB).
  0.2::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Bernhard is a swan' or 'Mary went to the bedroom' or both.