Chances are about even that Jeff moved to the garden. It is probably the case that Greg is gray. Chances are about even that Sandra took the milk. There is a better than even chance that if 'Sandra took the milk' or 'Greg is gray' or both then Julius is yellow. Chances are slight that if 'Sandra took the milk and Greg is gray' then Mary got the football. Chances are slight that if 'Greg is gray' or 'Sandra took the milk' or both then John went to the hallway.
We believe that 'Jeff moved to the garden' or 'Julius is yellow' or both.
We believe that 'Jeff moved to the garden' or 'Julius is yellow' or both.
We doubt that 'Jeff moved to the garden' or 'Julius is yellow' 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
  0.5::factA.
  0.7::factB.
  0.5::factC.
  %hop1
  0.6::factX:-or(factC,factB).
  0.1::factY:-and(factC,factB).
  0.1::factZ:-or(factB,factC).

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

  query(conclusion).
  
'Jeff moved to the garden' or 'Julius is yellow' or both.