We believe that Greg is a swan. It is probably not the case that Fred left the apple. It is improbable that John moved to the garden. It is almost certain that if 'Fred left the apple and John moved to the garden' then Winona is a wolf. It is highly unlikely that if either 'Greg is a swan' or 'John moved to the garden' but not both then Mary dropped the milk. It is unlikely that if 'Fred left the apple and John moved to the garden' then Julius is white.
It is likely that 'John moved to the garden' or 'Mary dropped the milk' or both.
Chances are slight that 'John moved to the garden' or 'Mary dropped the milk' or both.
It is likely that 'John moved to the garden' or 'Mary 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
  0.75::factA.
  0.25::factB.
  0.1::factC.
  %hop1
  0.95::factX:-and(factB,factC).
  0.05::factY:-xor(factA,factC).
  0.2::factZ:-and(factB,factC).

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

  query(conclusion).
  
'John moved to the garden' or 'Mary dropped the milk' or both.