Chances are slight that Mary left the milk. It is probably not the case that Greg is white. It is probably not the case that Lily is gray. There is little chance that if 'Lily is gray' or 'Greg is white' or both then Sumit is tired. We believe that if either 'Mary left the milk' or 'Lily is gray' but not both then Bill went to the office. It is unlikely that if 'Lily is gray' or 'Mary left the milk' or both then John moved to the garden.
It is probably not the case that 'John moved to the garden' or 'Lily is gray' or both.
It is probably not the case that 'John moved to the garden' or 'Lily is gray' or both.
It is probable that 'John moved to the garden' or 'Lily is gray' 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
  0.1::factA.
  0.25::factB.
  0.25::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.75::factY:-xor(factA,factC).
  0.2::factZ:-or(factC,factA).

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

  query(conclusion).
  
'John moved to the garden' or 'Lily is gray' or both.