It is certain that Bernhard is a frog. Chances are slight that Daniel got the football. Chances are about even that John went to the bedroom. It is impossible that if 'Daniel got the football and John went to the bedroom' then Sandra put down the milk. Chances are about even that if either 'John went to the bedroom' or 'Daniel got the football' but not both then Lily is green. It is improbable that if 'John went to the bedroom' or 'Daniel got the football' or both then Julius is a swan.
It is highly likely that 'Julius is a swan and Bernhard is a frog'.
It is highly unlikely that 'Julius is a swan and Bernhard is a frog'.
It is highly likely that 'Julius is a swan and Bernhard is a frog'.

  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.
  0.1::factB.
  0.5::factC.
  %hop1
  0.0::factX:-and(factB,factC).
  0.5::factY:-xor(factC,factB).
  0.1::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Julius is a swan and Bernhard is a frog'.