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Interdicting a criminal with limited police resources is a challenging task as the criminal changes location over time. The size of the large transportation network further adds to the difficulty of this scenario. To tackle this issue, we…

Artificial Intelligence · Computer Science 2026-04-08 Sukanya Samanta , Kei Kimura , Makoto Yokoo , Palash Dey

We present two efficient algorithms that compute the optimal strategy for cop in the game of Cop v.s. Gambler where the gambler's strategy is not optimal but known to the cop. The first algorithm is analogous to Bellman-Ford algorithm for…

Combinatorics · Mathematics 2017-01-11 Shen-Fu Tsai

We consider the minimum order graphs with a given cop number. We prove that the minimum order of a connected graph with cop number 3 is 10, and show that the Petersen graph is the unique isomorphism type of graph with this property. We…

We establish a lower bound for the cop number of graphs of high girth in terms of the minimum degree, and more generally, in terms of a certain growth condition. We show, in particular, that the cop number of any graph with girth $g$ and…

Combinatorics · Mathematics 2020-05-25 Peter Bradshaw , Seyyed Aliasghar Hosseini , Bojan Mohar , Ladislav Stacho

We show that the cop number of any graph on 18 or fewer vertices is at most 3. This answers a question posed by Andreae in 1986, as well as more recently by Baird et al. We also find all 3-cop-win graphs on 11 vertices, narrow down the…

Combinatorics · Mathematics 2025-10-29 Jérémie Turcotte , Samuel Yvon

We consider the localization game played on graphs, wherein a set of cops attempt to determine the exact location of an invisible robber by exploiting distance probes. The corresponding optimization parameter for a graph $G$ is called the…

Combinatorics · Mathematics 2020-01-27 Anthony Bonato , William B. Kinnersley

We introduce a new game played on graphs, ``Agents and Adversary". This game is reminiscent of ``Cops and Robbers" but has some fundamental differences. We classify infinite families of graphs as Agents-win and Adversary-win. We then define…

Combinatorics · Mathematics 2026-03-13 William K. Moses , Amanda Redlich , Frederick Stock

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

We consider a simple game, the $k$-regular graph game, in which players take turns adding edges to an initially empty graph subject to the constraint that the degrees of vertices cannot exceed $k$. We show a sharp topological threshold for…

Combinatorics · Mathematics 2014-01-23 Alan Frieze , Wesley Pegden

We study the Localization game on locally finite graphs trees, where each of the countably many vertices have finite degree. In contrast to the finite case, we construct a locally finite tree with localization number $n$ for any choice of…

Combinatorics · Mathematics 2024-04-04 Anthony Bonato , Florian Lehner , Trent G. Marbach , JD Nir

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 propose a definition of generalized Cops and Robbers games where there are two players, the Pursuer and the Evader, who each move via prescribed rules. If the Pursuer can ensure that the game enters into a fixed set of final positions,…

Combinatorics · Mathematics 2017-04-20 Anthony Bonato , Gary MacGillivray

Meyniel's conjecture states that $n$-vertex connected graphs have cop number $O(\sqrt{n})$. The current best known upper bound is $n/2^{(1-o(1))\sqrt{\log n}}$, proved independently by Lu and Peng (2011), and by Scott and Sudakov (2011). In…

Combinatorics · Mathematics 2026-02-10 Prosenjit Bose , Louis Esperet , Jędrzej Hodor , Gwenaël Joret , Piotr Micek , Clément Rambaud

We consider the Cops and Robber pursuit-evasion game when the edge-set of the graph is allowed to change in time, possibly at every round. Specifically, the game is played on an infinite periodic sequence $\mathcal{G} = (G_0, \dots,…

Discrete Mathematics · Computer Science 2024-10-31 Jean-Lou De Carufel , Paola Flocchini , Nicola Santoro , Frédéric Simard

We consider a pursuit-evasion game that describes the process of extinguishing a fire burning on the nodes of an undirected graph. We denote the minimum number of firefighters required by ffn(G) and provide almost sharp bounds to this graph…

Computational Complexity · Computer Science 2026-04-15 Julius Althoetmar , Jamico Schade , Torben Schürenberg

In this paper we consider the cop number of graphs with no, or few, short cycles. We show that when $G$ is graph of girth $g$ and the minimum degree $\delta \geq 2$, then $c(G) = O(n\log(n)(\delta-1)^{-\lfloor \frac{g+1}{4} \rfloor})$ as a…

Combinatorics · Mathematics 2024-07-22 Alexander Clow

The cops-and-robber (CR) game has been used in mobile robotics as a discretized model (played on a graph G) of pursuit/evasion problems. The "classic" CR version is a perfect information game: the cops' (pursuer's) location is always known…

Discrete Mathematics · Computer Science 2014-02-26 Athanasios Kehagias , Dieter Mitsche , Pawel Pralat

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

In 2019, Sivaraman conjectured that every $P_k$-free graph has cop number at most $k-3$. In the same year, Liu proved this conjecture for $(P_k,\text{claw})$-free graphs. Recently Chudnovsky, Norin, Seymour, and Turcotte proved this…

Combinatorics · Mathematics 2025-09-16 Alexander Clow , Erin Meger

"Zombies and Survivor" is a variant of the well-studied game of "Cops and Robber" where the zombies (cops) can only move closer to the survivor (robber). We consider the deterministic version of the game where a zombie can choose their path…

Combinatorics · Mathematics 2021-06-04 Valentin Bartier , Laurine Bénéteau , Marthe Bonamy , Hoang La , Jonathan Narboni