MathDB
Nondegenerate triangle game theory

Source: pOMA 2024/6

November 14, 2024
combinatorics

Problem Statement

Given a positive integer n3n\ge 3, Arándano and Banana play a game. Initially, numbers 1,2,3,,n1,2,3,\dots,n are written on the blackboard. Alternatingly and starting with Arándano, the players erase numbers from the board one at a time, until exactly three numbers remain on the board. Banana wins the game if the last three numbers on the board are the sides of a nondegenerate triangle, and Arándano wins otherwise. Determine, in terms of nn, who has a winning strategy.