It is almost certain that Julius is a swan. It is highly unlikely that Jason is tired. It is impossible that Sandra dropped the milk. It is probably not the case that if either 'Julius is a swan' or 'Sandra dropped the milk' but not both then Winona is a sheep. Chances are slight that if 'Julius is a swan' or 'Sandra dropped the milk' or both then Jeff left the football. It is probably not the case that if 'Julius is a swan and Sandra dropped the milk' then Bill went to the kitchen.
Chances are slight that 'Jeff left the football' or 'Sandra dropped the milk' or both.
Chances are slight that 'Jeff left the football' or 'Sandra dropped the milk' or both.
There is a very good chance that 'Jeff left the football' or 'Sandra dropped the milk' 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
  0.95::factA.
  0.05::factB.
  0.0::factC.
  %hop1
  0.25::factX:-xor(factA,factC).
  0.1::factY:-or(factA,factC).
  0.25::factZ:-and(factA,factC).

  %hop2
  conclusion:-or(factY,factC).

  query(conclusion).
  
'Jeff left the football' or 'Sandra dropped the milk' or both.