Vertex Removal and Vertex-Edge Domination
Abstract
A vertex v of a graph G ve-dominates every edge incident with a vertex in its closed neighborhood NG[v]. A set of vertices is a vertex-edge dominating set (ve-dominating set) if every edge of G is ve-dominated by some vertex in the set. The minimum cardinality of such a set is the vertex-edge domination number γve(G), also known as the isolation number. In this paper, we study the effect of vertex removal on γve(G), establish sharp bounds on γve(G−v) and characterize the vertices whose removal decreases, preserves, or increases γve(G). Let V0(G) and V+(G) denote the sets of vertices whose removal preserves and increases γve(G), respectively, and let Vfix0(G) consist of the vertices in V0(G) belonging to every minimum ve-dominating set. We prove that |V0(G)|≥3|Vfix0(G)|+∑v∈ V+(G) (γve(G−v)−γve(G)+1). In particular, |V0(G)|≥ 2|V+(G)|. We also prove that every vertex in Vfix0(G) lies on a cycle and that V0(T)≠∅ for every tree T of order at least three.
Related
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BibTeX
@misc{li2026vertex,
title = {{Vertex Removal and Vertex-Edge Domination}},
author = {Minhui Li and Shumin Zhang and Fengming Dong},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.26912},
eprint = {2610.26912},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.26912},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Vertex Removal and Vertex-Edge Domination
AU - Minhui Li
AU - Shumin Zhang
AU - Fengming Dong
PY - 2026
DA - 2026/10/17
PB - arXiv
DO - 10.48550/arxiv.2610.26912
UR - https://arxiv.org/abs/2610.26912
AB - A vertex v of a graph G ve-dominates every edge incident with a vertex in its closed neighborhood N_G[v]. A set of vertices is a vertex-edge dominating set (ve-dominating set) if every edge of G is ve-dominated by some vertex in the set. The minimum cardinality of such a set is the vertex-edge domination number γ_ve(G), also known as the isolation number. In this paper, we study the effect of vertex removal on γ_ve(G), establish sharp bounds on γ_ve(G−v) and characterize the vertices whose removal decreases, preserves, or increases γ_ve(G). Let V^0(G) and V^+(G) denote the sets of vertices whose removal preserves and increases γ_ve(G), respectively, and let V_fix^0(G) consist of the vertices in V^0(G) belonging to every minimum ve-dominating set. We prove that |V^0(G)|≥3|V_fix^0(G)|+∑_v∈ V^+(G) (γ_ve(G−v)−γ_ve(G)+1). In particular, |V^0(G)|≥ 2|V^+(G)|. We also prove that every vertex in V_fix^0(G) lies on a cycle and that V^0(T)≠∅ for every tree T of order at least three.
ER -