It is probable that Antoine is thirsty. It is improbable that Sandra dropped the milk. Chances are slight that Greg is a frog. It is highly unlikely that if 'Antoine is thirsty and Sandra dropped the milk' then Bernhard is a swan. It is unlikely that if 'Antoine is thirsty' or 'Greg is a frog' or both then Julius is a lion. We believe that if 'Sandra dropped the milk' or 'Antoine is thirsty' or both then Gertrude is a wolf.
We believe that 'Bernhard is a swan and Antoine is thirsty'.
It is impossible that 'Bernhard is a swan and Antoine is thirsty'.
We believe that 'Bernhard is a swan and Antoine is thirsty'.

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

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

  query(conclusion).
  
'Bernhard is a swan and Antoine is thirsty'.