Sankaku-Tori: An Old Western-Japanese Game Played on a Point Set
We study a combinatorial game named “sankaku-tori” in Japanese, which means “triangle-taking” in English. It is an old pencil-and-paper game for two players played in Western Japan. The game is played on points on the plane in general position. In each turn, a player adds a line segment to join two points, and the game ends when a triangulation of the point set is completed. The player who completes more triangles than the other wins. In this paper, we consider two restricted variants of this game. In the first variant, the first player always wins in a nontrivial way, and the second variant is NP-complete in general.
KeywordsLine Segment Maximum Match Winning Strategy Incidence Graph Matching Edge
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