English

On the spanning connectivity of tournaments

Combinatorics 2017-06-16 v1

Abstract

Let DD be a digraph. A kk-container of DD between uu and vv, C(u,v)C(u,v), is a set of kk internally disjoint paths between uu and vv. A kk-container C(u,v)C(u,v) of DD is a strong (resp. weak) kk^{*}-container if there is a set of kk internally disjoint paths with the same direction (resp. with different directions allowed) between uu and vv and it contains all vertices of DD. A digraph DD is kk^{*}-strongly (resp. kk^{*}-weakly) connected if there exists a strong (resp. weak) kk^{*}-container between any two distinct vertices. We define the strong (resp. weak) spanning connectivity of a digraph DD, κs(D)\kappa_{s}^{*}(D) (resp. κw(D)\kappa_{w}^{*}(D) ), to be the largest integer kk such that DD is ω\omega^{*}-strongly (resp. ω\omega^{*}-weakly) connected for all 1ωk1\leq \omega\leq k if DD is a 11^{*}-strongly (resp. 11^{*}-weakly) connected. In this paper, we show that a tournament with nn vertices and irregularity i(T)ki(T)\leq k, if n6t+5kn\geq6t+5k (t2)(t\geq2), then κs(T)t\kappa_{s}^{*}(T)\geq t and κw(T)t+1\kappa_{w}^{*}(T)\geq t+1 if n6t+5k3n\geq6t+5k-3 (t2)(t\geq2).

Keywords

Cite

@article{arxiv.1706.04742,
  title  = {On the spanning connectivity of tournaments},
  author = {Bo Zhang and Weihua Yang and Shurong Zhang},
  journal= {arXiv preprint arXiv:1706.04742},
  year   = {2017}
}

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11 pages