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Related papers: Cops and Robbers on Graphs with Path Constraints

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We prove that every connected $P_5$-free graph has cop number at most two, solving a conjecture of Sivaraman. In order to do so, we first prove that every connected $P_5$-free graph $G$ with independence number at least three contains a…

Combinatorics · Mathematics 2025-10-29 Maria Chudnovsky , Sergey Norin , Paul Seymour , Jérémie Turcotte

We prove that the cop number of any $2K_2$-free graph is at most 2, proving a conjecture of Sivaraman and Testa. We also show that the upper bound of $3$ on the cop number of $2K_1+K_2$-free (co-diamond--free) graphs is best possible.

Combinatorics · Mathematics 2025-10-29 Jérémie Turcotte

The game of cops and robber is a turn based vertex pursuit game played on a connected graph between a team of cops and a single robber. The cops and the robber move alternately along the edges of the graph. We say the team of cops win the…

Combinatorics · Mathematics 2022-11-30 Uttam K. Gupta , Suchismita Mishra , Dinabandhu Pradhan

The game of cops and robber is a two-player turn-based game played on a graph where the cops try to capture the robber. The cop number of a graph $G$, denoted by $c(G)$ is the minimum number of cops required to capture the robber. For a…

Discrete Mathematics · Computer Science 2025-05-22 Arnab Char , Paras Vinubhai Maniya , Dinabandhu Pradhan

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

We generalise the popular cops and robbers game to multi-layer graphs, where each cop and the robber are restricted to a single layer (or set of edges). We show that initial intuition about the best way to allocate cops to layers is not…

Combinatorics · Mathematics 2026-02-10 Jessica Enright , Kitty Meeks , William Pettersson , John Sylvester

We prove that the cop number of a $2K_2$-free graph is at most $2$ if it has diameter $3$ or does not have an induced cycle of length $k$, where $k \ \in \{3,4,5\}$. We conjecture that the cop number of every $2K_2$-free graph is at most…

Combinatorics · Mathematics 2019-03-28 Vaidy Sivaraman , Stephen Testa

In the game of Cops and Robber, a team of cops attempts to capture a robber on a graph $G$. Initially, all cops occupy some vertices in $G$ and the robber occupies another vertex. In each round, a cop can move to one of its neighbors or…

Combinatorics · Mathematics 2019-09-02 Mingrui Liu

In this paper, we study the game of cops and robber on the class of graphs with no even hole (induced cycle of even length) and claw (a star with three leaves). The cop number of a graph $G$ is defined as the minimum number of cops needed…

Combinatorics · Mathematics 2022-01-12 Ramin Javadi , Ali Momeni

A hole in a graph is an induced cycle of length at least 4. We give a simple winning strategy for t-3 cops to capture a robber in the game of cops and robbers played in a graph that does not contain a hole of length at least t. This…

Combinatorics · Mathematics 2020-01-03 Vaidy Sivaraman

The game of \emph{Cops and Robber} is usually played on a graph, where a group of cops attempt to catch a robber moving along the edges of the graph. The \emph{cop number} of a graph is the minimum number of cops required to win the game.…

Combinatorics · Mathematics 2024-04-29 Joshua Erde , Mihyun Kang , Florian Lehner , Bojan Mohar , Dominik Schmid

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

In this paper, the notions of {\em trapping} and {\em confining} the robber on a graph are introduced. We present some structural necessary conditions for graphs $G$ not containing the path on $k$ vertices (referred to as $P_k$-free graphs)…

Combinatorics · Mathematics 2020-09-15 Masood Masjoody

In the game of cops and robber, the cops try to capture a robber moving on the vertices of the graph. The minimum number of cops required to win on a given graph $G$ is called the cop number of $G$. The biggest open conjecture in this area…

Combinatorics · Mathematics 2018-09-25 Pawel Pralat , Nicholas Wormald

In the game of cops and robber, the cops try to capture a robber moving on the vertices of the graph. The minimum number of cops required to win on a given graph $G$ is called the cop number of $G$. The biggest open conjecture in this area…

Combinatorics · Mathematics 2014-12-12 Pawel Pralat , Nick Wormald

We consider the cop-throttling number of a graph $G$ for the game of Cops and Robbers, which is defined to be the minimum of $(k + \text{capt}_k(G))$, where $k$ is the number of cops and $\text{capt}_k(G)$ is the minimum number of rounds…

Combinatorics · Mathematics 2018-02-27 Jane Breen , Boris Brimkov , Joshua Carlson , Leslie Hogben , K. E. Perry , Carolyn Reinhart

Andreae (1986) proved that the cop number of connected $H$-minor-free graphs is bounded for every graph $H$. In particular, the cop number is at most $|E(H-h)|$ if $H-h$ contains no isolated vertex, where $h\in V(H)$. The main result of…

Combinatorics · Mathematics 2025-10-29 Franklin Kenter , Erin Meger , Jérémie Turcotte

Cops and Robber is a well-studied two-player pursuit-evasion game played on a graph, where a group of cops tries to capture the robber. The \emph{cop number} of a graph is the minimum number of cops required to capture the robber.…

Discrete Mathematics · Computer Science 2025-04-11 Sandip Das , Harmender Gahlawat

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

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…

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