Gobang is PSPACE-complete
For many games, the decision problem of whether a player in a given situation has a winning strategy has been shown to be PSPACE-complete. Following the PSPACE-completeness results of Even and Tarjan  for generalized Hex on graphs and of Schaefer  for a variety of combinatorial games, the decision problems were shown to be PSPACE-hard for generalizations of Go and Checkers. In this paper a corresponding theorem is proved for the board-game Gobang, a variant of Go. Since the decision problem for Gobang states-of-play itself lies in PSPACE, it can be shown that Gobang is in fact PSPACE-complete.
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