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The localization game is a pursuit-evasion game analogous to Cops and Robbers, where the robber is invisible and the cops send distance probes in an attempt to identify the location of the robber. We present a novel graph parameter called…

Combinatorics · Mathematics 2021-05-21 Natalie C. Behague , Anthony Bonato , Melissa A. Huggan , Trent G. Marbach , Brittany Pittman

Cops and Robber is a family of two-player games played on graphs in which one player controls a number of cops and the other player controls a robber. In alternating turns, each player moves (all) their figures. The cops try to capture the…

Combinatorics · Mathematics 2024-01-11 Minh Tuan Ha , Paul Jungeblut , Torsten Ueckerdt , Paweł Żyliński

Cops and Robbers is a pursuit-evasion game played on graphs, of which many variants have been developed and studied. We introduce a variant of this game, "Sneaky-Active Cops and Robbers", where all cops and robber must move on their turn,…

Combinatorics · Mathematics 2026-03-16 Tien Chih , Laura Scull

A gambler moves between the vertices $1, \ldots, n$ of a graph using the probability distribution $p_{1}, \ldots, p_{n}$. Multiple cops pursue the gambler on the graph, only being able to move between adjacent vertices. We investigate the…

Discrete Mathematics · Computer Science 2016-10-11 Jesse Geneson

We define new graph parameters, called flip-width, that generalize treewidth, degeneracy, and generalized coloring numbers for sparse graphs, and clique-width and twin-width for dense graphs. The flip-width parameters are defined using…

Combinatorics · Mathematics 2024-03-26 Szymon Toruńczyk

In this paper we analyze and model three open problems posed by Harris, Insko, Prieto-Langarica, Stoisavljevic, and Sullivan in 2020 concerning the tipsy cop and robber game on graphs. The three different scenarios we model account for…

Combinatorics · Mathematics 2021-03-01 Viktoriya Bardenova , Vincent Ciarcia , Erik Insko

We explore a variant of the game of Cops and Robber introduced by Bonato et al.~where the robber is invisible unless outside the common neighbourhood of the cops. The hyperopic cop number is analogous to the cop number and we investigate…

Combinatorics · Mathematics 2021-07-16 Nancy E. Clarke , Stephen Finbow , Margaret-Ellen Messinger , Amanda Porter

We recall several known results about minimally 2-connected graphs, and show that they all follow from a decomposition theorem. Starting from an analogy with critically 2-connected graphs, we give structural characterizations of the classes…

Discrete Mathematics · Computer Science 2016-03-27 Pierre Aboulker , Marko Radovanović , Nicolas Trotignon , Kristina Vušković

We show that if $n=7k/i$ with $i \in \{1,2,3\}$ then the cop number of the generalised Petersen graph $GP(n,k)$ is $4$, with some small previously-known exceptions. It was previously proved by Ball et al. (2015) that the cop number of any…

Combinatorics · Mathematics 2020-09-03 Harmony Morris , Joy Morris

A hole is an induced cycle of length at least 4, and an odd hole is a hole of odd length. It is NP-hard to color the vertices of an odd hole-free graph. A graph $G$ is perfectly divisible if every induced subgraph $H$ of $G$ with at least…

Combinatorics · Mathematics 2026-03-11 Weihua He , Yueping Shi , Rong Wu , Zheng-an Yao

For each integer $\ell \geq 4$, we give a polynomial-time algorithm to test whether a graph contains an induced cycle with length at least $\ell$ and even

Combinatorics · Mathematics 2020-09-15 Linda Cook , Paul Seymour

A hole is an induced cycle of length at least 4, and an odd hole is a hole of odd length. A full house is a graph composed by a vertex adjacent to both ends of an edge in $K_4$ . Let $H$ be the complement of a cycle on 7 vertices.…

Discrete Mathematics · Computer Science 2021-10-26 Jialei Song , Baogang Xu

A graph is even-hole-free if it has no induced even cycles of length 4 or more. A cap is a cycle of length at least 5 with exactly one chord and that chord creates a triangle with the cycle. In this paper, we consider (cap, even hole)-free…

Discrete Mathematics · Computer Science 2016-11-28 Kathie Cameron , Murilo V. G. da Silva , Shenwei Huang , Kristina Vušković

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

\textit{Pursuit-evasion games} have been intensively studied for several decades due to their numerous applications in artificial intelligence, robot motion planning, database theory, distributed computing, and algorithmic theory.…

Discrete Mathematics · Computer Science 2023-07-11 Harmender Gahlawat , Meirav Zehavi

A theta is a graph formed by three paths between the same pair of distinct vertices so that the union of any two of the paths induces a hole. A wheel is a graph formed by a hole and a node that has at least 3 neighbors in the hole. In this…

Combinatorics · Mathematics 2023-10-23 Marko Radovanović , Nicolas Trotignon , Kristina Vušković

A hole in a graph is an induced cycle of length at least 4. A hole is long if its length is at least 5. By $P_t$ we denote a path on $t$ vertices. In this paper we give polynomial-time algorithms for the following problems: the Maximum…

Data Structures and Algorithms · Computer Science 2020-03-12 Tara Abrishami , Maria Chudnovsky , Marcin Pilipczuk , Paweł Rzążewski , Paul Seymour

A celebrated theorem of Stiebitz asserts that any graph with minimum degree at least $s+t+1$ can be partitioned into two parts which induce two subgraphs with minimum degree at least $s$ and $t$, respectively. This resolved a conjecture of…

Combinatorics · Mathematics 2017-06-23 Jie Ma , Tianchi Yang

Mohar recently adapted the classical game of Cops and Robber from graphs to metric spaces, thereby unifying previously studied pursuit-evasion games. He conjectured that finitely many cops can win on any compact geodesic metric space, and…

Combinatorics · Mathematics 2023-09-08 Agelos Georgakopoulos

Cop-width and flip-width are new families of graph parameters introduced by Toru\'nczyk (2023) that generalise treewidth, degeneracy, generalised colouring numbers, clique-width and twin-width. In this paper, we bound the cop-width and…

Combinatorics · Mathematics 2025-05-14 Robert Hickingbotham