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JOURNALS // Sibirskie Èlektronnye Matematicheskie Izvestiya [Siberian Electronic Mathematical Reports] // Archive

Sib. Èlektron. Mat. Izv., 2020 Volume 17, Pages 637–646 (Mi semr1237)

Discrete mathematics and mathematical cybernetics

Vertex colourings of multigraphs with forbiddances on edges

A. N. Glebova, I. A. Pavlovb, K. A. Khadaevc

a Sobolev Institute of Mathematics, 4, Koptyuga ave., Novosibirsk, 630090, Russia
b Novosibirsk State University, 2, Pirogova str., Novosibirsk, 630090, Russia
c Higher School of Economics, 20, Myasnitskaya str., Moscow, 101000, Russia

Abstract: We define and study a new class of vertex colourings of multigraphs, where some pairs of colours are forbidden on the edges of a multigraph. We say that a multigraph $G$ is (properly) $(m,r)$-colourable if for any given sets of $r$ forbidden pairs of colours on the edges of $G$ where exists a (proper) vertex $m$-colouring of $G$ that respects all forbidden pairs. We determine all (properly) $(m,r)$-colourable stars, all $(2,r)$-colourable multigraphs for each $r\ge 1$ and all $(m,r)$-colourable multighraphs, where $r$ is large enough (close to $m^2$). We also introduce a list version of $(m,r)$-colourability and establish (for the case of improper colourings) that the list $(m,r)$-colourability of a multigraph is equivalent to its $(m,r)$-colourability.

Keywords: graph, multigraph, edge, colouring, list colouring, forbiddance.

UDC: 519.172.2, 519.174

MSC: 05C10, 05C15, 05C70

Received November 3, 2018, published April 24, 2020

DOI: 10.33048/semi.2020.17.042



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