shortest paths on a 4x4 grid with obstacles
obstacles at 23, 24, and 33.  Start at 11, goal is 44

(11 12 CONNECTED)
(12 11 CONNECTED)
(21 22 CONNECTED)
(22 21 CONNECTED)
(31 32 CONNECTED)
(32 31 CONNECTED)
(41 42 CONNECTED)
(42 41 CONNECTED)

(12 13 CONNECTED)
(13 12 CONNECTED)
(42 43 CONNECTED)
(43 42 CONNECTED)

(13 14 CONNECTED)
(14 13 CONNECTED)
(43 44 CONNECTED)
(44 43 CONNECTED)

(11 21 CONNECTED)
(21 11 CONNECTED)
(21 31 CONNECTED)
(31 21 CONNECTED)
(31 41 CONNECTED)
(41 31 CONNECTED)

(12 22 CONNECTED)
(22 12 CONNECTED)
(22 32 CONNECTED)
(32 22 CONNECTED)
(32 42 CONNECTED)
(42 32 CONNECTED)

(34 44 CONNECTED)
(44 34 CONNECTED)

(preconds (at 11) )

(effects (at 44) )