How to Color Temporal Graphs to Ensure Proper Transitions

Fuente: arXiv
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Main Authors: Ibiapina, Allen, Nguyen, Minh Hang, Rabie, Mikaël, Robin, Cléophée
Format: Preprint
Published: 2025
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author Ibiapina, Allen
Nguyen, Minh Hang
Rabie, Mikaël
Robin, Cléophée
author_facet Ibiapina, Allen
Nguyen, Minh Hang
Rabie, Mikaël
Robin, Cléophée
contents Graph Coloring consists in assigning colors to vertices ensuring that two adjacent vertices do not have the same color. In dynamic graphs, this notion is not well defined, as we need to decide if different colors for adjacent vertices must happen all the time or not, and how to go from a coloring in one time to the next one. In this paper, we define a coloring notion for Temporal Graphs where at each step, the coloring must be proper. It uses a notion of compatibility between two consecutive snapshots that implies that the coloring stays proper while the transition happens. Given a graph, the minimum number of colors needed to ensure that such coloring exists is the \emph{Temporal Chromatic Number} of this graph. With those notions, we provide some lower and upper bounds for the temporal chromatic number in the general case. We then dive into some specific classes of graphs such as trees, graphs with bounded degree or bounded degeneracy. Finally, we consider temporal graphs where grow pace is one, that is, a single edge can be added and a single other one can be removed between two time steps. In that case, we consider bipartite and bounded degree graphs. Even though the problem is defined with full knowledge of the temporal graph, our results also work in the case where future snapshots are given online: we need to choose the coloring of the next snapshot after having computed the current one, not knowing what
format Preprint
id arxiv_https___arxiv_org_abs_2505_10207
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How to Color Temporal Graphs to Ensure Proper Transitions
Ibiapina, Allen
Nguyen, Minh Hang
Rabie, Mikaël
Robin, Cléophée
Discrete Mathematics
Graph Coloring consists in assigning colors to vertices ensuring that two adjacent vertices do not have the same color. In dynamic graphs, this notion is not well defined, as we need to decide if different colors for adjacent vertices must happen all the time or not, and how to go from a coloring in one time to the next one. In this paper, we define a coloring notion for Temporal Graphs where at each step, the coloring must be proper. It uses a notion of compatibility between two consecutive snapshots that implies that the coloring stays proper while the transition happens. Given a graph, the minimum number of colors needed to ensure that such coloring exists is the \emph{Temporal Chromatic Number} of this graph. With those notions, we provide some lower and upper bounds for the temporal chromatic number in the general case. We then dive into some specific classes of graphs such as trees, graphs with bounded degree or bounded degeneracy. Finally, we consider temporal graphs where grow pace is one, that is, a single edge can be added and a single other one can be removed between two time steps. In that case, we consider bipartite and bounded degree graphs. Even though the problem is defined with full knowledge of the temporal graph, our results also work in the case where future snapshots are given online: we need to choose the coloring of the next snapshot after having computed the current one, not knowing what
title How to Color Temporal Graphs to Ensure Proper Transitions
topic Discrete Mathematics
url https://arxiv.org/abs/2505.10207