English

$k$-Domination invariants on Kneser graphs

Combinatorics 2023-12-27 v1

Abstract

In this follow-up to [M.G.~Cornet, P.~Torres, arXiv:2308.15603], where the kk-tuple domination number and the 2-packing number in Kneser graphs K(n,r)K(n,r) were studied, we are concerned with two variations, the kk-domination number, γk(K(n,r)){\gamma_{k}}(K(n,r)), and the kk-tuple total domination number, γt×k(K(n,r)){\gamma_{t\times k}}(K(n,r)), of K(n,r)K(n,r). For both invariants we prove monotonicity results by showing that γk(K(n,r))γk(K(n+1,r)){\gamma_{k}}(K(n,r))\ge {\gamma_{k}}(K(n+1,r)) holds for any n2(k+r)n\ge 2(k+r), and γt×k(K(n,r))γt×k(K(n+1,r)){\gamma_{t\times k}}(K(n,r))\ge {\gamma_{t\times k}}(K(n+1,r)) holds for any n2r+1n\ge 2r+1. We prove that γk(K(n,r))=γt×k(K(n,r))=k+r{\gamma_{k}}(K(n,r))={\gamma_{t\times k}}(K(n,r))=k+r when nr(k+r)n\geq r(k+r), and that in this case every γk{\gamma_{k}}-set and γt×k{\gamma_{t\times k}}-set is a clique, while γk(r(k+r)1,r)=γt×k(r(k+r)1,r)=k+r+1{\gamma_{k}}(r(k+r)-1,r)={\gamma_{t\times k}}(r(k+r)-1,r)=k+r+1, for any k2k\ge 2. Concerning the 2-packing number, ρ2(K(n,r))\rho_2(K(n,r)), of K(n,r)K(n,r), we prove the exact values of ρ2(K(3r3,r))\rho_2(K(3r-3,r)) when r10r\ge 10, and give sufficient conditions for ρ2(K(n,r))\rho_2(K(n,r)) to be equal to some small values by imposing bounds on rr with respect to nn. We also prove a version of monotonicity for the 22-packing number of Kneser graphs.

Cite

@article{arxiv.2312.15464,
  title  = {$k$-Domination invariants on Kneser graphs},
  author = {Boštjan Brešar and María Gracia Cornet and Tanja Dravec and Michael A. Henning},
  journal= {arXiv preprint arXiv:2312.15464},
  year   = {2023}
}

Comments

15 pages, 3 tables

R2 v1 2026-06-28T14:01:00.718Z