Through Allis' solution etc... P1 can force a win if he places the first stone in the highlighted region. Assuming both players have perfect information, it will take 41 turns maximum (if I recall correctly) for P1 to force a win.
Anyways, back to my question... In the game which I have posted an image of, assuming that P1 (the plus) is to move first, how can P1 force a win in the given situation?
I'm just having trouble with visualing the game, any input whatsoever would be appreciated.
Thanks.
Solution:
(where red denotes "plus" and blue denotes "minus")
1 represents the first move, 2 represents the second move etc...
P1 can essentially backwardly induce his best strategy. P1 would play (1) first. Since P2 has no immediate way of winning the game, he is forced to play (2) in order to avoid losing. P1 would then play (3) in order to set up another possible win. Once again, P2 is forced to block by playing (4).
P1 would then play (5). P2 has two options now, put a stone where the label "p1 win" is or put one at 6. Regardless of which move P2 takes, P1 will win on his next move.