We believe that Jason is tired. It is improbable that Greg is white. It is highly likely that Mary left the football. It is probable that if either 'Jason is tired' or 'Mary left the football' but not both then Lily is a frog. It is highly unlikely that if either 'Greg is white' or 'Jason is tired' but not both then Winona is a cat. It is improbable that if 'Greg is white' or 'Jason is tired' or both then John dropped the milk.
It is almost certain that 'John dropped the milk' or 'Greg is white' or both.
We doubt that 'John dropped the milk' or 'Greg is white' or both.
It is almost certain that 'John dropped the milk' or 'Greg is white' 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.
  0.1::factB.
  0.9::factC.
  %hop1
  0.7::factX:-xor(factA,factC).
  0.05::factY:-xor(factB,factA).
  0.1::factZ:-or(factB,factA).

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

  query(conclusion).
  
'John dropped the milk' or 'Greg is white' or both.