Go? Go where?

[Yoruichi-san]

Being the extraordinary cheapskates *cough* multi-taskers we are, the Chinese have developed a bevy of games utilizing a wei chi set.

One such game is Connect Five, in which (like it sounds) black and white take turns laying down pieces until one player has a line of five pieces (horizontal, vertical, or diagonal) and wins.

Assuming both players are actually trying to win, what is the maximum size (square) board on which the game could end in a tie?

[bonanova]

It's less than sixteen.

We played this little gem of a game as kids, and someone always won.

[Prime]

I played that game in my childhood on square ruled paper. In Russia we called the game tic tac toe on an infinite board, or Chinese checkers.

I've never seen anyone prooving a forced win. Although, starting side has an advantage.

[phil1882]

based on the wkipedia article http://en.wikipedia.org/wiki/Gomoku

i'd say 10x10.

Edited February 15, 2013 by phil1882

[Yoruichi-san]

Yeah, the game is one that can be and to some degree has been 'solved' in terms of forcing sequences, the question can be alternatively asked what is the minimum forcing sequence?

[Prime]

I don't believe the game was solved 40 years ago, when I used to play it occasionally. I did not solve it then, even though I was younger and my brain worked faster.

The game could be solved with a computer program, I suppose (if there is a forced win.)

I don't understand what "solved to some degree" means. If it is solved there must be an answer in terms of the number of moves required at the most (to win.) Whereas the longest (in terms of number of moves) required path to the win may not be necessarily the one requiring the largest square board. There may be spacially longer winning paths with less moves.

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