A Strategy for Maker in the Clique Game which Helps to Tackle some Open Problems by Beck (0909.4362v2)

Abstract: We study Maker/Breaker games on the edges of the complete graph, as introduced by Chvatal and Erdos. We show that in the (m:b) clique game played on K_{N}, the complete graph on N vertices, Maker can achieve a K_{q} for q = (m/(log_{2}(b + 1)) - o(1)) * log N, which partially solves an open problem by Beck. Moreover, we show that in the (1:1) clique game played on K_{N} for a sufficiently large N, Maker can achieve a K_{q} in only 2^2q/3 moves, which improves the previous best bound and answers a question of Beck. Finally we consider the so called tournament game. A tournament is a directed graph where every pair of vertices is connected by a single directed edge. The tournament game is played on K_{N}. At the beginning Breaker fixes an arbitrary tournament T_{q} on q vertices. Maker and Breaker then alternately take turns at claiming one unclaimed edge e and selecting one of the two possible orientations. Maker wins if his graph contains a copy of the goal tournament T_{q}; otherwise Breaker wins. We show that Maker wins the tournament game on K_{N} with q = (1 - o(1))*log_{2}(N) which supports the random graph intuition: the threshold for q is asymptotically the same for the game played by two "clever'' players and the game played by two ``random'' players. This last result solves an open problem of Beck which he included in his list of the seven most humiliating open problems.