We believe that Gertrude is a mouse. It is highly likely that Lily is green. It is probably not the case that Sandra left the milk. It is highly unlikely that if 'Lily is green' or 'Gertrude is a mouse' or both then John dropped the milk. There is a very good chance that if 'Sandra left the milk' or 'Lily is green' or both then Julius is a frog. It is highly likely that if 'Sandra left the milk and Lily is green' then Daniel took the apple.
We believe that 'John dropped the milk' or 'Julius is a frog' or both.
We believe that 'John dropped the milk' or 'Julius is a frog' or both.
It is probably not the case that 'John dropped the milk' or 'Julius is a frog' 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.
  0.9::factB.
  0.25::factC.
  %hop1
  0.05::factX:-or(factB,factA).
  0.8::factY:-or(factC,factB).
  0.9::factZ:-and(factC,factB).

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

  query(conclusion).
  
'John dropped the milk' or 'Julius is a frog' or both.