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We tackle three optimization problems in which a colored graph, where each node is assigned a color, must be partitioned into colorful connected components. A component is defined as colorful if each color appears at most once. The problems…

Combinatorics · Mathematics 2025-06-11 Claudia Archetti , Martina Cerulli , Carmine Sorgente

Graph Neural Networks (GNNs) have emerged as an efficient alternative to convolutional approaches for vision tasks such as image classification, leveraging patch-based representations instead of raw pixels. These methods construct graphs…

Computer Vision and Pattern Recognition · Computer Science 2025-04-29 Nikolaos Chaidos , Angeliki Dimitriou , Nikolaos Spanos , Athanasios Voulodimos , Giorgos Stamou

Edge lengths of a graph are called flexible if there exist infinitely many non-congruent realizations of the graph in the plane satisfying these edge lengths. It has been shown recently that a graph has flexible edge lengths if and only if…

Combinatorics · Mathematics 2021-02-05 Georg Grasegger , Jan Legerský , Josef Schicho

We say that a vertex or edge colouring of a graph is distinguishing if the only automorphism that preserves this colouring is the identity. A (proper) distinguishing colouring is irreducible if there is no possibility of merging two…

Combinatorics · Mathematics 2026-02-18 Marcin Stawiski

A temporal graph is a graph whose edges only appear at certain points in time. Reachability in these graphs is defined in terms of paths that traverse the edges in chronological order (temporal paths). This form of reachability is neither…

Computational Complexity · Computer Science 2024-07-01 Arnaud Casteigts , Nils Morawietz , Petra Wolf

We study the problem of colouring visibility graphs of polygons. In particular, for visibility graphs of simple polygons, we provide a polynomial algorithm for 4-colouring, and prove that the 5-colourability question is already NP-complete…

Combinatorics · Mathematics 2019-06-06 Onur Çağirici , Petr Hliněný , Bodhayan Roy

Inspired by earlier results about proper and polychromatic coloring of hypergraphs, we investigate such colorings of directed hypergraphs, that is, hypergraphs in which the vertices of each hyperedge is partitioned into two parts, a tail…

Combinatorics · Mathematics 2022-05-24 Balázs Keszegh

The problems studied in this paper originate from Graph Motif, a problem introduced in 2006 in the context of biological networks. Informally speaking, it consists in deciding if a multiset of colors occurs in a connected subgraph of a…

Computational Complexity · Computer Science 2014-09-11 Romeo Rizzi , Florian Sikora

This paper introduces a new variant of domination-related coloring of graphs, which is a combination of their dominator coloring and equitable coloring called the equitable dominator coloring. An equitable coloring is a proper coloring in…

Combinatorics · Mathematics 2024-08-27 Phebe Sarah George , S. Madhumitha , Sudev Naduvath

This paper serves as the first extension of the topic of dominator colorings of graphs to the setting of digraphs. We establish the dominator chromatic number over all possible orientations of paths and cycles. In this endeavor we discover…

Combinatorics · Mathematics 2019-02-21 Michael Cary

One of the questions in Rigidity Theory is whether a realization of the vertices of a graph in the plane is flexible, namely, if it allows a continuous deformation preserving the edge lengths. A flexible realization of a connected graph in…

Computational Geometry · Computer Science 2025-12-11 Petr Laštovička , Jan Legerský

In this paper we consider aspects of geometric observability for hypergraphs, extending our earlier work from the uniform to the nonuniform case. Hypergraphs, a generalization of graphs, allow hyperedges to connect multiple nodes and…

Dynamical Systems · Mathematics 2024-04-12 Joshua Pickard , Cooper Stansbury , Amit Surana , Indika Rajapakse , Anthony Bloch

Graph colouring is a fundamental problem for networks, serving as a tool for avoiding conflicts via symmetry breaking, for example, avoiding multiple computer processes simultaneously updating the same resource. This paper considers a…

Data Structures and Algorithms · Computer Science 2025-11-26 Duncan Adamson , George B. Mertzios , Paul G. Spirakis

The graph-navigability problem concerns how one can find as short paths as possible between a pair of vertices, given an incomplete picture of a graph. We study the navigability of graphs where the vertices are tagged by a number (between 1…

Physics and Society · Physics 2011-08-25 Sang Hoon Lee , Petter Holme

In an edge-colored graph, a traversal cost occurs at a vertex along a path when consecutive edges with different colors are traversed. The value of the traversal cost depends only on the colors of the traversed edges. This concept leads to…

Data Structures and Algorithms · Computer Science 2016-07-25 Didem Gözüpek , Mordechai Shalom

In this paper we resolve the complexity of the isomorphism problem on all but finitely many of the graph classes characterized by two forbidden induced subgraphs. To this end we develop new techniques applicable for the structural and…

Discrete Mathematics · Computer Science 2014-11-10 Pascal Schweitzer

When many colors appear in edge-colored graphs, it is only natural to expect rainbow subgraphs to appear. This anti-Ramsey problem has been studied thoroughly and yet there remain many gaps in the literature. Expanding upon classical and…

Combinatorics · Mathematics 2019-05-30 Chuandong Xu , Colton Magnant , Shenggui Zhang

Graph neural networks (GNNs) have been extensively developed for graph representation learning in various application domains. However, similar to all other neural networks models, GNNs suffer from the black-box problem as people cannot…

Machine Learning · Computer Science 2022-03-18 Peibo Li , Yixing Yang , Maurice Pagnucco , Yang Song

Persistent homology, a technique from computational topology, has recently shown strong empirical performance in the context of graph classification. Being able to capture long range graph properties via higher-order topological features,…

Machine Learning · Computer Science 2024-12-20 Rubén Ballester , Bastian Rieck

Clique-width is one of the graph complexity measures leading to polynomial special-case algorithms for generally NP-complete problems, e.g. graph colourability. The best two currently known algorithms for verifying c-colourability of graphs…

Computational Complexity · Computer Science 2021-08-13 Bruno Courcelle , Irène Durand , Michael Raskin