English

Forcibly unicyclic and bicyclic graphic sequences

Combinatorics 2025-04-23 v1

Abstract

A sequence D=(d1,d2,,dn)D=(d_1,d_2,\ldots,d_n) of non-negative integers is called a graphic sequence if there is a simple graph with vertices v1,v2,,vnv_1,v_2,\ldots,v_n such that the degree of viv_i is did_i for 1in1\leq i\leq n. Given a graph theoretical property P\mathcal{P}, a graphic sequence DD is forcibly P\mathcal{P} graphic if each graph with degree sequence DD has property P\mathcal{P}. A graph is acyclic if it contains no cycles. A connected acyclic graph is just a tree and has n1n-1 edges. A graph of order nn is unicyclic (resp. bicyclic) if it is connected and has nn (resp. n+1n+1) edges. Bar-Noy, B\"{o}hnlein, Peleg and Rawitz [Discrete Mathematics 346 (2023) 113460] characterized forcibly acyclic and forcibly connected acyclic graphic sequences. In this paper, we aim to characterize forcibly unicyclic and forcibly bicyclic graphic sequences.

Keywords

Cite

@article{arxiv.2504.15596,
  title  = {Forcibly unicyclic and bicyclic graphic sequences},
  author = {Peiyi Duan and Yingzhi Tian},
  journal= {arXiv preprint arXiv:2504.15596},
  year   = {2025}
}
R2 v1 2026-06-28T23:06:43.248Z