Permutations of counters on a table

TL;DR

This paper analyzes a game involving setting counters on a rotating regular polygon table, providing a complete characterization of when the player can win based on the parameters and group actions involved.

Contribution

The authors generalize previous results by characterizing winning conditions for a broader class of group actions on counters, extending the understanding of the game's combinatorial structure.

Findings

Player can win iff n=1, m=1, or (n, m) are powers of the same prime.

Simplifies and extends Bar Yehuda et al.'s argument to broader group actions.

Provides a complete characterization of winning strategies for the game.

Abstract

We consider a game in which a blindfolded player attempts to set $n$ counters lying on the vertices of a rotating regular $n$-gon table simultaneously to $0$. When the counters count$\pmod{m}$ we simplify the argument of Bar Yehuda, Etzion, and Moran (1993) showing that the player can win if and only if $n = 1$, $m = 1$, or $(n, m) = (p^a, p^b)$ for some prime $p$ and $a, b \in \mathbb{N}$. We broadly generalize the result to the setting where the counters can be permuted by any element of a subset of the symmetric group $S \subseteq S_n$, with the original formulation corresponding to $S = \mathbb{Z}_n$ (rotations of the table).