# Queens in exile: non-attacking queens on infinite chess boards

## TL;DR

This paper investigates placing non-attacking queens on infinite and semi-infinite chessboards with specific numbering schemes, providing a comprehensive solution for the infinite case using the Tribonacci word and exploring related combinatorial game connections.

## Contribution

It offers a detailed solution for non-attacking queens placement on infinite chessboards with unique numbering, introducing novel combinatorial methods and linking to combinatorial game theory.

## Key findings

- Complete solution for Z x Z infinite chessboard using Tribonacci word
- Analysis of N x N chessboard with numbering along antidiagonals
- Connections established between queen placement and combinatorial games

## Abstract

Number the cells of a (possibly infinite) chessboard in some way with the numbers 0, 1, 2, ... Consider the cells in order, placing a queen in a cell if and only if it would not attack any earlier queen. The problem is to determine the positions of the queens. We study the problem for a doubly-infinite chessboard of size Z x Z numbered along a square spiral, and an infinite single-quadrant chessboard (of size N x N) numbered along antidiagonals. We give a fairly complete solution in the first case, based on the Tribonacci word. There are connections with combinatorial games.