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Meagan Mann

Publications and source records attributed to Meagan Mann.

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Reproducing the k-copwin Algorithm: Theory vs. Implementation

Cops and Robbers is a well-studied pursuit-evasion game that provides insights into graph theory and theoretical computing. A central question is determining the minimum number of cops required to capture the robber, known as the cop number. We focus on reproducing an algorithm proposed by Petr, Portier, and Versteegen in 2022, which efficiently determines whether a graph is $k$-copwin. This paper presents a Python implementation of the $k$-copwin algorithm. In this work, we present our implementation in detail, clarify key aspects of the algorithm, and discuss its implications for future practical deployments.

math.CO

Domain Design for the Cops and Robbers Problem

Cops and Robbers is a well-studied problem in graph theory. The setting consists of a robber and one or more cops placed on an undirected graph. Taking turns moving throughout the graph, the cops try to capture the robber. The property of interest is whether $k$ cops suffice to ensure at least one cop occupies the same vertex as the robber, after a finite number of turns, given any configuration of their initial placement; if successful, the graph is referred to as ``$k$-copwin''. In this work, we cast the problem of determining whether a graph is $k$-copwin as a non-deterministic planning problem and use state-of-the-art planners to compute this property. The cop movement is cast as non-deterministic movement (to capture all possible strategies), while the robber movement is deterministic in nature. We also extend the base model using several variations from the graph theory literature.

cs.GT

Predicting The Cop Number Using Machine Learning

Cops and Robbers is a pursuit evasion game played on a graph, first introduced independently by Quilliot \cite{quilliot1978jeux} and Nowakowski and Winkler \cite{NOWAKOWSKI1983235} over four decades ago. A main interest in recent the literature is identifying the cop number of graph families. The cop number of a graph, $c(G)$, is defined as the minimum number of cops required to guarantee capture of the robber. Determining the cop number is computationally difficult and exact algorithms for this are typically restricted to small graph families. This paper investigates whether classical machine learning methods and graph neural networks can accurately predict a graph's cop number from its structural properties and identify which properties most strongly influence this prediction. Of the classical machine learning models, tree-based models achieve high accuracy in prediction despite class imbalance, whereas graph neural networks achieve comparable results without explicit feature engineering. The interpretability analysis shows that the most predictive features are related to node connectivity, clustering, clique structure, and width parameters, which aligns with known theoretical results. Our findings suggest that machine learning approaches can be used in complement with existing cop number algorithms by offering scalable approximations where computation is infeasible.

cs.LG