It is highly unlikely that Jason is tired. We believe that Lily is a swan. There is almost no chance that John left the football. We believe that if 'John left the football' or 'Lily is a swan' or both then Julius is a frog. It is certain that if either 'John left the football' or 'Lily is a swan' but not both then Brian is white. There is little chance that if 'Jason is tired and Lily is a swan' then Bernhard is a lion.
It is impossible that 'Bernhard is a lion and Lily is a swan'.
It is impossible that 'Bernhard is a lion and Lily is a swan'.
It is probable that 'Bernhard is a lion and Lily is a swan'.

  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
  0.05::factA.
  0.75::factB.
  0.02::factC.
  %hop1
  0.75::factX:-or(factC,factB).
  1.0::factY:-xor(factC,factB).
  0.1::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Bernhard is a lion and Lily is a swan'.