There is almost no chance that Lily is gray. There is a very good chance that John got the apple. It is certain that Greg is white. It is impossible that if either 'Greg is white' or 'Lily is gray' but not both then Daniel left the milk. There is little chance that if 'Lily is gray and John got the apple' then Julius is a rhino. We believe that if 'Greg is white' or 'Lily is gray' or both then Mary moved to the garden.
It is certain that 'Mary moved to the garden' or 'Greg is white' or both.
It is certain that 'Mary moved to the garden' or 'Greg is white' or both.
Chances are about even that 'Mary moved to the garden' 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
  0.02::factA.
  0.8::factB.
  1.0::factC.
  %hop1
  0.0::factX:-xor(factC,factA).
  0.1::factY:-and(factA,factB).
  0.75::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Mary moved to the garden' or 'Greg is white' or both.