Abstract
A path in a vertex-coloured graph is called conflict-free if there is a colour used on exactly one of its vertices. A vertex-coloured graph is said to be conflict-free vertex-connected if any two distinct vertices of the graph are connected by at least one conflict-free vertex-path. The conflict-free vertex-connection number, denoted by vcfc(G), is the smallest number of colours needed in order to make G conflict-free vertex-connected. Our main result of this paper is the following: Let G be a connected graph of order \(n\ge 11\). If \(\delta (G)\ge \frac{n}{5}\), then \(vcfc(G)\le 3\). Moreover, we show that both bounds, on the order n and the minimum degree \(\delta (G)\), are tight. Furthermore, we generalize our result by requiring minimum degree-sum conditions for pairs, triples or quadruples of independent vertices.
Similar content being viewed by others
Availability of data and materials
Not applicable.
Code availability
Not applicable.
References
Andrews, E., Laforge, E., Lumduanhom, C., Zhang, P.: On proper-path colorings in graphs. J. Combin. Math. Combin. Comput. 97, 189–207 (2016)
Brause, C., Doan, T.D., Schiermeyer, I.: Minimum degree conditions for the proper connection number of graphs. Graphs Combin. 33, 833–843 (2017). https://doi.org/10.1007/s00373-017-1796-1
Brause, C., Doan, T.D., Schiermeyer, I.: On the minimum degree and the proper connection number of graphs. Electron. Notes Discrete Math. 55, 109–112 (2016)
Borozan, V., Fujita, S., Gerek, A., Magnant, C., Manoussakis, Y., Montero, L., Tuza, Z.: Proper connection of graphs. Discrete Math. 312, 2550–2560 (2012)
Chartrand, G., Johns, G.L., McKeon, K.A., Zhang, P.: Rainbow connection in graphs. Math. Bohemica 133(1), 85–98 (2008)
Chizmar, E., Magnant, C., Nowbandegani, P.S.: Note on vertex and total proper connection numbers. AKCE Int. J. Graphs Combin. 13(2), 103–106 (2016)
Chang, H., Doan, T.D., Huang, Z., Jendrol’, S., Li, X., Schiermeyer, I.: Graphs with conflict-free connection number two. Graphs Combin. 34, 1553–1563 (2018)
Czap, J., Jendrol’, S., Valiska, J.: Conflict-free connections of graphs. Discuss. Math. Graph Theory 38(4), 911–920 (2018)
Chen, L., Li, X., Shi, Y.: The complexity of determining the rainbow vertex-connection of a graph. Theor. Comput. Sci. 412(35), 4531–4535 (2011)
Doan, T.D., Schiermeyer, I.: Conflict-free vertex connection number at most \(3\) and size of graphs. Discuss. Math. Graph Theory 41, 617–632 (2021)
Doan, T.D., Schiermeyer, I.: Conflict-free connection number and size of graphs. Graphs Combin. 37, 1859–1871 (2021)
Jiang, H., Li, X., Zhang, Y., Zhao, Y.: On (Strong) proper vertex-connection of graphs. Bull. Malays. Math. Sci. Soc. 41(1), 415–425 (2018)
Krivelevich, M., Yuster, R.: The rainbow connection of a graph is (at most) reciprocal to its minimum degree. J. Graph Theory 63(3), 185–191 (2010)
Li, X., Shi, Y., Sun, Y.: Rainbow connections of graphs: a survey. Graphs Combin. 29, 1–38 (2013)
Li, X., Sun, Y.: Rainbow Connections of Graphs. Springer Briefs in Mathematics. Springer, New York (2012)
Li, X., Magnant, C.: Properly colored notions of connectivity—a dynamic survey. Theory Appl. Graphs 0(1) (2015) (Art. 2)
Li, X., Zhang, Y., Zhu, X., Mao, Y., Zhao, H., Jendrol’, S.: Conflict-free vertex-connections of graphs. Discuss. Math. Graph Theory 40, 51–65 (2020)
Li, Z., Wu, B.: On the maximum value of conflict-free vertex-connection number of graphs. Discrete Math. Algor. Appl. 10(05) (2018)
West, D.B.: Introduction to Graph Theory. Prentice Hall, Hoboken (2001)
Acknowledgements
We would like to thank the two reviewers for several valuable comments and suggestions improving this paper. A part of work was completed during a stay of the second author at the Vietnam Institute for Advanced Study in Mathematics (VIASM). He would like to thank this institution for financial support and hospitality.
Funding
This research was partly supported by Vietnam Ministry of Education and Training under grant number B2022-BKA-03.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
Not applicable.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Doan, T.D., Ha, P.H. & Schiermeyer, I. The Conflict-Free Vertex-Connection Number and Degree Conditions of Graphs. Graphs and Combinatorics 38, 157 (2022). https://doi.org/10.1007/s00373-022-02567-y
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00373-022-02567-y