PreprintCC BY 4.0arXiv
Strong edge-colourings of truncations of cubic graphs
Abstract
We study a problem posed by Kardoš asking whether the truncation of every connected simple bridgeless cubic graph has strong chromatic index six. The truncation T(G) is obtained by replacing each vertex of G with a triangle and attaching its incident edges to distinct vertices of that triangle. An affirmative answer was previously established for prism bases by Han and Cui. We prove that sidx(T(G))=6 whenever G is a connected simple cubic graph that is bipartite or is both bridgeless and claw-free. Both proofs are constructive and use a common compatibility criterion for combining colourings of smaller pieces. The bipartite result also extends to non-det-extremal multigraphs.
Related
BibTeX
@misc{labbate2026strong,
title = {{Strong edge-colourings of truncations of cubic graphs}},
author = {Domenico Labbate and Federico Romaniello},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41950},
eprint = {2610.41950},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41950},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Strong edge-colourings of truncations of cubic graphs
AU - Domenico Labbate
AU - Federico Romaniello
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41950
UR - https://arxiv.org/abs/2610.41950
AB - We study a problem posed by Kardoš asking whether the truncation of every connected simple bridgeless cubic graph has strong chromatic index six. The truncation T(G) is obtained by replacing each vertex of G with a triangle and attaching its incident edges to distinct vertices of that triangle. An affirmative answer was previously established for prism bases by Han and Cui. We prove that sidx(T(G))=6 whenever G is a connected simple cubic graph that is bipartite or is both bridgeless and claw-free. Both proofs are constructive and use a common compatibility criterion for combining colourings of smaller pieces. The bipartite result also extends to non-det-extremal multigraphs.
ER -