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2-Edge-Colored Chromatic Number of Grids is at Most 9
Graphs and Combinatorics ( IF 0.7 ) Pub Date : 2020-03-11 , DOI: 10.1007/s00373-020-02155-y
Janusz Dybizbański

A 2-edge-colored graph is a pair \((G, \sigma )\) where G is a graph, and \(\sigma :E(G)\rightarrow \{\text {'}+\text {'},\text {'}-\text {'}\}\) is a function which marks all edges with signs. A 2-edge-colored coloring of the 2-edge-colored graph \((G, \sigma )\) is a homomorphism into a 2-edge-colored graph \((H, \delta )\). The 2-edge-colored chromatic number of the 2-edge-colored graph \((G, \sigma )\) is the minimum order of H. In this paper we show that for every 2-dimensional grid \((G, \sigma )\) there exists a homomorphism from \((G, \sigma )\) into the 2-edge-colored Paley graph \(SP_9\). Hence, the 2-edge-colored chromatic number of the 2-edge-colored grids is at most 9. This improves the upper bound on this number obtained recently by Bensmail. Additionally, we show that 2-edge-colored chromatic number of the 2-edge-colored grids with 3 columns is at most 8.



中文翻译:

网格的2边色色数最多为9

2边色图是一对\((G,\ sigma)\),其中G是图,而\(\ sigma:E(G)\ rightarrow \ {\ text {'} + \ text {' },\ text {'}-\ text {'} \} \)是用符号标记所有边缘的函数。2边色图\((G,\ sigma)\)的2边色着色是2边色图\((H,\ delta)\)的同态。2边彩色图\((G,\ sigma)\)的2边彩色色数是H的最小阶。在本文中,我们表明,对于每个二维网格\((G,\ sigma)\),存在从\(((G,\ sigma)\)到2边色Paley图的同态\(SP_9 \)。因此,2边彩色网格的2边彩色色数最多为9。这改善了Bensmail最近获得的该数字的上限。此外,我们显示具有3列的2边缘色网格的2边缘色色数最多为8。

更新日期:2020-03-11
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