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PreprintarXiv licencearXiv

The Borodin--Kostochka Conjecture for Two Classes of Diamond-Free Graphs

Abstract

We prove the Borodin--Kostochka conjecture for (diamond,L4)-free graphs and (diamond,K5+)-free graphs, where L4 is obtained from K4 by attaching a path of length two to one clique vertex, and K5+ is obtained from K5 by adding a vertex adjacent to exactly one clique vertex. The proof uses structural properties of maximum cliques in diamond-free vertex-critical graphs with χ=Δ.

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BibTeX
@misc{fiujlaali2026borodinkostochka,
  title = {{The Borodin--Kostochka Conjecture for Two Classes of Diamond-Free Graphs}},
  author = {Alireza Fiujlaali},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.40279},
  eprint = {2610.40279},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.40279},
}
RIS
TY  - UNPB
TI  - The Borodin--Kostochka Conjecture for Two Classes of Diamond-Free Graphs
AU  - Alireza Fiujlaali
PY  - 2026
DA  - 2026/10/29
PB  - arXiv
DO  - 10.48550/arxiv.2610.40279
UR  - https://arxiv.org/abs/2610.40279
AB  - We prove the Borodin--Kostochka conjecture for (diamond,L_4)-free graphs and (diamond,K_5^+)-free graphs, where L_4 is obtained from K_4 by attaching a path of length two to one clique vertex, and K_5^+ is obtained from K_5 by adding a vertex adjacent to exactly one clique vertex. The proof uses structural properties of maximum cliques in diamond-free vertex-critical graphs with χ=Δ.
ER  -