Volume 96, Issue 1 pp. 137-159
ARTICLE

Proper-walk connection number of graphs

Jørgen Bang-Jensen

Corresponding Author

Jørgen Bang-Jensen

Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark

Correspondence Jørgen Bang-Jensen, Department of Mathematics and Computer Science, University of Southern Denmark, Odense DK5230, Denmark.

Email: [email protected]

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Thomas Bellitto

Thomas Bellitto

Institute of Informatics, Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Warsaw, Poland

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Anders Yeo

Anders Yeo

Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark

Department of Pure and Applied Mathematics, University of Johannesburg, Johannesburg, South Africa

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We dedicate this paper to Ron Graham whose enormous energy, friendly attitude, open mindedness and countless contributions to science has always been a great inspiration
First published: 30 June 2020
Citations: 4

Abstract

This paper studies the problem of proper-walk connection number: given an undirected connected graph, our aim is to colour its edges with as few colours as possible so that there exists a properly coloured walk between every pair of vertices of the graph, that is, a walk that does not use consecutively two edges of the same colour. The problem was already solved on several classes of graphs but still open in the general case. We establish that the problem can always be solved in polynomial time in the size of the graph and we provide a characterization of the graphs that can be properly connected with k colours for every possible value of k.

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