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JOURNALS // Proceedings of the Yerevan State University, series Physical and Mathematical Sciences // Archive

Proceedings of the YSU, Physical and Mathematical Sciences, 2025 Volume 59, Issue 2, Pages 32–45 (Mi uzeru1137)

Mathematics

On semistrong edge-colorings of outerplanar graphs

A. Ê. Drambyana, N. P. Mikaelyanb

a Russian-Armenian University, Yerevan
b Yerevan State University

Abstract: A matching $M$ of a graph $G$ is called semistrong, if every edge of $M$ has a vertex of degree one in the induced subgraph by the vertices of $M$. A semistrong edge-coloring of a graph $G$ is a proper edge-coloring in which every color class induces a semistrong matching. The minimum number of colors required for a semistrong edge-coloring is called the semistrong chromatic index of $G$ and denoted by $\chi'_{ss}(G)$. In this paper, we propose a new approach for constructing semistrong edge-colorings and provide an upper bound on the semistrong chromatic index of outerplanar graphs.

Keywords: edge-coloring, semistrong edge-coloring, semistrong chromatic index, outerplanar graphs

MSC: 05C15

Received: 16.05.2025
Revised: 12.06.2025
Accepted: 25.06.2025

Language: English

DOI: 10.46991/PYSU:A.2025.59.2.032



© Steklov Math. Inst. of RAS, 2026