Chances are slight that John picked up the apple. It is certain that Jessica is a sheep. It is certain that Brian is white. We doubt that if 'Brian is white' or 'John picked up the apple' or both then Winona is a cat. It is likely that if 'Jessica is a sheep' or 'Brian is white' or both then Bernhard is a swan. It is improbable that if 'John picked up the apple' or 'Jessica is a sheep' or both then Julius is a rhino.
It is almost certain that 'Bernhard is a swan and John picked up the apple'.
It is highly unlikely that 'Bernhard is a swan and John picked up the apple'.
It is almost certain that 'Bernhard is a swan and John picked up the apple'.

  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.
  1.0::factB.
  1.0::factC.
  %hop1
  0.2::factX:-or(factC,factA).
  0.7::factY:-or(factB,factC).
  0.1::factZ:-or(factA,factB).

  %hop2
  conclusion:-and(factY,factA).

  query(conclusion).
  
'Bernhard is a swan and John picked up the apple'.