The following table has only some "single" borders as indicated:

Top-Left (no left)	Top-Right (no top, no right)
Bottom-Left (no table border except for what's implicit in right-adjacent cell)	Bottom-Right (no bottom, no left)

The following table has no borders whatsoever:

(1,1)	(1,2)
(2,1)	(2,2)

The following table has double borders everywhere:

(1,1)	(1,2)
(2,1)	(2,2)