,
Paloma T. Lima
,
Roohani Sharma
Creative Commons Attribution 4.0 International license
The b-Coloring problem, which given a graph G and an integer k asks whether G has a proper k-coloring such that each color class has a vertex adjacent to all color classes except its own, is known to be FPT parameterized by the vertex cover number and XP and 𝖶[1]-hard parameterized by clique-width. Its complexity when parameterized by the treewidth of the input graph remained an open problem. We settle this question by showing that b-Coloring is XNLP-complete when parameterized by the pathwidth of the input graph. Besides determining the precise parameterized complexity of this problem, this implies that b-Coloring parameterized by pathwidth is 𝖶[t]-hard for all t, and resolves the parameterized complexity of b-Coloring parameterized by treewidth. We complement this result by showing that b-Coloring is FPT when parameterized by neighborhood diversity and by twin cover, two parameters that generalize vertex cover to more dense graphs, but are incomparable to pathwidth.
@InProceedings{jaffke_et_al:LIPIcs.ISAAC.2023.40,
author = {Jaffke, Lars and Lima, Paloma T. and Sharma, Roohani},
title = {{Structural Parameterizations of b-Coloring}},
booktitle = {34th International Symposium on Algorithms and Computation (ISAAC 2023)},
pages = {40:1--40:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-289-1},
ISSN = {1868-8969},
year = {2023},
volume = {283},
editor = {Iwata, Satoru and Kakimura, Naonori},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2023.40},
URN = {urn:nbn:de:0030-drops-193429},
doi = {10.4230/LIPIcs.ISAAC.2023.40},
annote = {Keywords: b-coloring, structural parameterization, XNLP, pathwidth, neighborhood diversity, twin cover}
}