English
Related papers

Related papers: Cops and robbers in random graphs

200 papers

We show that the expected time for a smart "cop" to catch a drunk "robber" on an $n$-vertex graph is at most $n + {\rm o}(n)$. More precisely, let $G$ be a simple, connected, undirected graph with distinguished points $u$ and $v$ among its…

Combinatorics · Mathematics 2014-11-05 Natasha Komarov , Peter Winkler

Cops and Robbers games have been studied for the last few decades in computer science and mathematics. As in general pursuit evasion games, pursuers (cops) seek to capture evaders (robbers); however, players move in turn and are constrained…

Discrete Mathematics · Computer Science 2020-04-27 Frédéric Simard , Josée Desharnais , François Laviolette

We show that the cop number of the Cayley sum graph of a finite group $G$ with respect to a symmetric subset $S$ is at most twice its degree when the graph is connected, undirected. We also prove that a similar bound holds for the cop…

Combinatorics · Mathematics 2025-04-29 Arindam Biswas , Jyoti Prakash Saha

In the `Covering' pursuit game on a graph, a robber and a set of cops play alternately, with the cops each moving to an adjacent vertex (or not moving) and the robber moving to a vertex at distance at most 2 from his current vertex. The aim…

Combinatorics · Mathematics 2025-04-22 Benjamin Gillott

The cop throttling number of a graph, introduced in 2018 by Breen et al., optimizes the balance between the number of cops used and the number of rounds required to catch the robber in a game of Cops and Robbers. In 2019, Cox and Sanaei…

Combinatorics · Mathematics 2020-07-14 Joshua Carlson , Robin Eagleton , Jesse Geneson , John Petrucci , Carolyn Reinhart , Preetul Sen

In a pursuit evasion game on a finite, simple, undirected, and connected graph $G$, a first player visits vertices $m_1,m_2,\ldots$ of $G$, where $m_{i+1}$ is in the closed neighborhood of $m_i$ for every $i$, and a second player probes…

Combinatorics · Mathematics 2018-01-09 Dennis Dayanikli , Dieter Rautenbach

We consider a variant of the Cops and Robbers game where the robber can move t edges at a time, and show that in this variant, the cop number of a d-regular graph with girth larger than 2t+2 is Omega(d^t). By the known upper bounds on the…

Combinatorics · Mathematics 2011-06-03 Abbas Mehrabian

The localization game is a two player combinatorial game played on a graph $G=(V,E)$. The cops choose a set of vertices $S_1 \subseteq V$ with $|S_1|=k$. The robber then chooses a vertex $v \in V$ whose location is hidden from the cops, but…

Combinatorics · Mathematics 2022-09-07 Lyuben Lichev , Dieter Mitsche , Pawel Pralat

We study the localization game on dense random graphs. In this game, a {\em cop} $x$ tries to locate a {\em robber} $y$ by asking for the graph distance of $y$ from every vertex in a sequence of sets $W_1,W_2,\ldots,W_\ell$. We prove high…

Combinatorics · Mathematics 2019-05-16 Andrzej Dudek , Alan Frieze , Wesley Pegden

The deduction game may be thought of as a variant on the classical game of cops and robber in which the cops (searchers) aim to capture an invisible robber (evader); each cop is allowed to move at most once, and cops situated on different…

Combinatorics · Mathematics 2025-10-30 Andrea C. Burgess , Nancy E. Clarke , Shannon L. Fitzpatrick , Melissa A. Huggan

We consider the cops and robber game variant consisting of one cop and one robber on time-varying graphs (TVG). The considered TVGs are edge periodic graphs, i.e., for each edge, a binary string $s_e$ determines in which time step the edge…

Computational Complexity · Computer Science 2021-07-13 Nils Morawietz , Petra Wolf

This paper introduced a pursuit and evasion game to be played on a connected graph. One player moves invisibly around the graph, and the other player must guess his position. At each time step the second player guesses a vertex, winning if…

Combinatorics · Mathematics 2017-01-24 John Haslegrave

The cop number of a graph $G$ is the smallest $k$ such that $k$ cops win the game of cops and robber on $G$. We investigate the maximum cop number of geometric intersection graphs, which are graphs whose vertices are represented by…

We show that if $\{G_n\}_{n\geq 1}$ is a sequence of graphs of order $n$ with bounded maximum degree and isoperimetric function $\Phi(G_n,n^{1-\alpha})$ bounded away from $0$ as $n\rightarrow \infty$, then the cop number of $G_n$ is at most…

Combinatorics · Mathematics 2024-02-12 Alexander Clow

We introduce the bodyguard problem for graphs. This is a variation of Surrounding Cops and Robber but, in this model, a smallest possible group of bodyguards must surround the president and then maintain this protection indefinitely. We…

Combinatorics · Mathematics 2025-08-15 Nancy E. Clarke , Danny Dyer , William Kellough

We adapt the Gy\'{a}rf\'{a}s path argument to prove that $t-2$ cops can capture a robber, in at most $t-1$ moves, in the game of cops and robbers played in a graph that does not contain the $t$-vertex path as an induced subgraph.

Combinatorics · Mathematics 2019-03-06 Vaidy Sivaraman

The game of cops and robber has been studied for many years. Denoting $\mathsf{Forb}(4K_1)$ to be the family of all graphs that contain no induced subgraph isomorphic to $4K_1$ (e.g., with independence number less than $4$), we prove that…

Combinatorics · Mathematics 2026-01-15 Zhaoyu Wu

A (finite or infinite) graph is called constructible if it may be obtained recursively from the one-point graph by repeatedly adding dominated vertices. In the finite case, the constructible graphs are precisely the cop-win graphs, but for…

Combinatorics · Mathematics 2022-08-02 Maria-Romina Ivan , Imre Leader , Mark Walters

In many variants of the game of Cops and Robbers on graphs, multiple cops play against a single robber. In 2019, Cox and Sanaei introduced a variant of the game that gives the robber a more active role than simply evading the cop. In their…

Combinatorics · Mathematics 2022-05-17 Joshua Carlson , Meghan Halloran , Carolyn Reinhart

We show that the cop number of directed and undirected Cayley graphs on abelian groups has an upper bound of the form of $O(\sqrt{n})$, where $n$ is the number of vertices, by introducing a refined inductive method. With our method, we…

Combinatorics · Mathematics 2025-10-29 Peter Bradshaw , Seyyed Aliasghar Hosseini , Jérémie Turcotte