player II can prevent player I from winning in a game on infinite square board
Source: Israel Grosman Memorial Mathematical Olympiad 1995 p2
February 15, 2020
combinatoricsgamegame strategywinning strategy
Problem Statement
Two players play a game on an infinite board that consists of unit squares. Player chooses a square and marks it with . Then player chooses another square and marks it with . They play until one of the players marks a whole row or a whole column of five consecutive squares, and this player wins the game. If no player can achieve this, the result of the game is a tie. Show that player can prevent player from winning.