English

Extremal spectral radius and $g$-good $r$-component connectivity

Combinatorics 2024-11-05 v1

Abstract

For FV(G)F\subseteq V(G), if GFG-F is a disconnected graph with at least rr components and each vertex vV(G)\Fv\in V(G)\backslash F has at least gg neighbors, then FF is called a gg-good rr-component cut of GG. The gg-good rr-component connectivity of GG, denoted by cκg,r(G)c\kappa_{g,r}(G), is the minimum cardinality of gg-good rr-component cuts of GG. Let Gnk,δ\mathcal{G}_n^{k,\delta} be the set of graphs of order nn with minimum degree δ\delta and gg-good rr-component connectivity cκg,r(G)=kc\kappa_{g,r}(G)=k. In the paper, we determine the extremal graphs attaining the maximum spectral radii among all graphs in Gnk,δ\mathcal{G}_n^{k,\delta}. A subset FV(G)F\subseteq V(G) is called a gg-good neighbor cut of GG if GFG-F is disconnected and each vertex vV(G)\Fv\in V(G)\backslash F has at least gg neighbors. The gg-good neighbor connectivity κg(G)\kappa_g(G) of a graph GG is the minimum cardinality of gg-good neighbor cuts of GG. The condition of gg-good neighbor connectivity is weaker than that of gg-good rr-component connectivity, and there is no requirement on the number of components. As a counterpart, we also study similar problem for gg-good neighbor connectivity.

Keywords

Cite

@article{arxiv.2411.01854,
  title  = {Extremal spectral radius and $g$-good $r$-component connectivity},
  author = {Wenxiu Ding and Dan Li and Yu Wang},
  journal= {arXiv preprint arXiv:2411.01854},
  year   = {2024}
}
R2 v1 2026-06-28T19:46:59.609Z