It is highly likely that Jeff discarded the milk. It is impossible that Julius is a frog. It is probable that Lily is white. There is a better than even chance that if either 'Lily is white' or 'Julius is a frog' but not both then Jason is tired. It is certain that if 'Jeff discarded the milk and Lily is white' then Sandra took the football. It is improbable that if 'Lily is white' or 'Jeff discarded the milk' or both then John dropped the apple.
We believe that 'John dropped the apple' or 'Lily is white' or both.
We believe that 'John dropped the apple' or 'Lily is white' or both.
It is impossible that 'John dropped the apple' or 'Lily 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
  0.9::factA.
  0.0::factB.
  0.7::factC.
  %hop1
  0.6::factX:-xor(factC,factB).
  1.0::factY:-and(factA,factC).
  0.1::factZ:-or(factC,factA).

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

  query(conclusion).
  
'John dropped the apple' or 'Lily is white' or both.