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We consider a new probabilistic graph searching game played on graphs, inspired by the familiar game of Cops and Robbers. In Zombies and Survivors, a set of zombies attempts to eat a lone survivor loose on a given graph. The zombies…

Discrete Mathematics · Computer Science 2015-03-31 Anthony Bonato , Dieter Mitsche , Xavier Pérez-Giménez , Paweł Prałat

We study the game of Cops and Robbers, where cops try to capture a robber on the vertices of a graph. Meyniel's conjecture states that for every connected graph $G$ on $n$ vertices, the cop number of $G$ is upper bounded by $O(\sqrt{n})$,…

Combinatorics · Mathematics 2019-09-09 Fatemeh Hasiri , Igor Shinkar

We pose a new and intriguing question motivated by distributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the…

Probability · Mathematics 2007-11-20 Noga Alon , Chen Avin , Michal Koucky , Gady Kozma , Zvi Lotker , Mark R. Tuttle

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

We introduce and study the game of "Selfish Cops and Active Robber" (SCAR) which can be seen as an multiplayer variant of the "classic" two-player Cops and Robbers (CR) game. In classic CR all cops are controlled by a single player, who has…

Discrete Mathematics · Computer Science 2018-09-13 G. Konstantinidis , Ath. Kehagias

The game of cops and robbers is a pursuit game on graphs where a set of agents, called the cops try to get to the same position of another agent, called the robber. Cops and robbers has been studies on several classes of graphs including…

Combinatorics · Mathematics 2019-03-19 Seyyed Aliasghar Hosseini , Masood Masjoody , Ladislav Stacho

Consider the time T_oz when the random walk on a weighted graph started at the vertex o first hits the vertex set z. We present lower bounds for T_oz in terms of the volume of z and the graph distance between o and z. The bounds are for…

Probability · Mathematics 2011-11-10 Balint Virag

The traditional game of cops and robbers is played on undirected graph. Recently, the same game played on directed graph is getting attention by more and more people. We knew that if we forbid some subgraph we can bound the cop number of…

Combinatorics · Mathematics 2020-01-29 Mingrui Liu

We study zombies and survivor, a variant of the game of cops and robber on graphs. In this variant, the single survivor plays the role of the robber and attempts to escape from the zombies that play the role of the cops. The zombies are…

Combinatorics · Mathematics 2022-04-27 Prosenjit Bose , Jean-Lou De Carufel , Thomas Shermer

We study a game of pursuit and evasion introduced by Seager in 2012, in which a cop searches the robber from outside the graph, using distance queries. A graph on which the cop wins is called locatable. In her original paper, Seager asked…

Combinatorics · Mathematics 2014-02-13 Richard A. B. Johnson , Sebastian Koch

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

In this paper, we answer two open problems from [Breen et al., Throttling for the game of Cops and Robbers on graphs, Discrete Math., 341 (2018) 2418-2430]. The throttling number $th_c(G)$ of a graph $G$ is the minimum possible value of $k…

Combinatorics · Mathematics 2019-10-23 Jesse Geneson

Aigner and Fromme initiated the systematic study of the cop number of a graph by proving the elegant and sharp result that in every connected planar graph, three cops are sufficient to win a natural pursuit game against a single robber.…

Combinatorics · Mathematics 2015-07-07 Po-Shen Loh , Siyoung Oh

Given a connected graph $G$ with some subset of its vertices excited and a fixed target vertex, in the geodesic-biased random walk on $G$, a random walker moves as follows: from an unexcited vertex, she moves to a uniformly random…

Probability · Mathematics 2019-09-13 Mikhail Beliayeu , Petr Chmel , Bhargav Narayanan , Jan Petr

In this paper we analyze a variant of the pursuit-evasion game on a graph $G$ where the intruder occupies a vertex, is allowed to move to adjacent vertices or remain in place, and is 'invisible' to the searcher, meaning that the searcher…

Combinatorics · Mathematics 2022-04-07 Anton Bernshteyn , Eugene Lee

We consider the model of limited visibility Cops and Robbers, where the cops can only see within their $l$-neighbourhood. We prove that the number of cops needed to see the robber can be arbitrarily smaller than the number needed to capture…

Combinatorics · Mathematics 2025-07-02 Bojan Bašić , Alfie Davies , Aleksa Džuklevski , Strahinja Gvozdić , Yannick Mogge

The game of Cops and Robber is traditionally played on a finite graph. The purpose of this note is to introduce and analyze the game that is played on an arbitrary geodesic space. The game is defined in such a way that it preserves the…

Combinatorics · Mathematics 2021-12-07 Bojan Mohar

We investigate multiple variants of the game Cops and Robbers. Playing it on an $n \times n$ toroidal chess graph, the game is varied by defining moves for cops and robbers differently, always mimicking moves of certain chess pieces. In…

Combinatorics · Mathematics 2018-10-26 Allyson Hahn , Neil R. Nicholson

We consider the Cops and Robbers game played on finite simple graphs. In a graph $G$, the number of cops required to capture a robber in the Cops and Robbers game is denoted by $c(G)$. For all graphs $G$, $c(G) \leq \alpha(G) \leq…

Combinatorics · Mathematics 2025-07-22 Alexander Clow , Imed Zaguia

We introduce two variations of the cops and robber game on graphs. These games yield two invariants in $\mathbb{Z}_+\cup\{\infty\}$ for any connected graph $\Gamma$, the {weak cop number $\mathsf{wcop}(\Gamma)$} and the {strong cop number…

Combinatorics · Mathematics 2023-06-22 Jonathan Lee , Eduardo Martínez-Pedroza , Juan Felipe Rodríguez-Quinche