English

Antimagic and product antimagic graphs with pendant edges

Combinatorics 2024-05-10 v1

Abstract

Let G=(V,E)G=(V,E) be a simple graph of size mm and LL a set of mm distinct real numbers. An LL-labeling of GG is a bijection ϕ:EL\phi: E \rightarrow L. We say that ϕ\phi is an antimagic LL-labeling if the induced vertex sum ϕ+:VR\phi_+: V \rightarrow \mathbb {R} defined as ϕ+(u)=uvEϕ(uv)\phi_+(u)=\sum_{uv\in E}\phi(uv) is injective. Similarly, ϕ\phi is a product antimagic LL-labeling of GG if the induced vertex product ϕ:VR\phi_{\circ}: V \rightarrow \mathbb {R} defined as ϕ(u)=uvEϕ(uv)\phi_{\circ}(u)=\prod_{uv\in E}\phi(uv) is injective. A graph GG is antimagic (resp. product antimagic) if it has an antimagic (resp. a product antimagic) LL-labeling for L={1,2,,m}L=\{1,2,\dots,m\}. Hartsfield and Ringel conjectured that every simple connected graph distinct from K2K_2 is antimagic, but the conjecture remains widely open. We prove, among other results, that every connected graph of size mm, m3m \geq 3, admits an antimagic LL-labeling for every arithmetic sequence LL of mm positive real numbers, if every vertex of degree at least three is a support vertex. As a corollary, we derive that these graphs are antimagic, reinforcing the veracity of the conjecture by Hartsfield and Ringel. Moreover, these graphs admit also a product antimagic LL-labeling provided that the smallest element of LL is at least one. The proof is constructive.

Keywords

Cite

@article{arxiv.2405.05375,
  title  = {Antimagic and product antimagic graphs with pendant edges},
  author = {Mercè Mora and Joaquín Tey},
  journal= {arXiv preprint arXiv:2405.05375},
  year   = {2024}
}

Comments

20 pages, 6 figures