Simplicity in Eulerian circuits : Uniqueness and safety

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2024-01

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Mcode

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Language

en

Pages

5
1-5

Series

Information Processing Letters, Volume 183

Abstract

An Eulerian circuit in a directed graph is one of the most fundamental Graph Theory notions. Detecting if a graph G has a unique Eulerian circuit can be done in polynomial time via the BEST theorem by de Bruijn, van Aardenne-Ehrenfest, Smith and Tutte (1941–1951) [15,16] (involving counting arborescences), or via a tailored characterization by Pevzner, 1989 (involving computing the intersection graph of simple cycles of G), both of which thus rely on overly complex notions for the simpler uniqueness problem. In this paper we give a new linear-time checkable characterization of directed graphs with a unique Eulerian circuit. This is based on a simple condition of when two edges must appear consecutively in all Eulerian circuits, in terms of cut nodes of the underlying undirected graph of G. As a by-product, we can also compute in linear-time all maximal safe walks appearing in all Eulerian circuits, for which Nagarajan and Pop proposed in 2009 [12] a polynomial-time algorithm based on Pevzner characterization.

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Funding Information: We are very grateful to the anonymous reviewers who helped improved the presentation of this paper. This work was partially funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 851093 , SAFEBIO) and partially by the Academy of Finland (grants No. 322595 , 328877 , 314284 and 335715 ). Publisher Copyright: © 2023 The Author(s)

Keywords

BEST theorem, Cut node, Eulerian circuit, Graph Algorithms, Safety

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Citation

Obscura Acosta, N & Tomescu, A I 2024, ' Simplicity in Eulerian circuits : Uniqueness and safety ', Information Processing Letters, vol. 183, 106421, pp. 1-5 . https://doi.org/10.1016/j.ipl.2023.106421