Irredundance Trees of Diameter 3
Abstract
A set D of vertices of a graph G with vertex set V is irredundant if each non-isolated vertex of G[D] has a neighbour in V-D that is not adjacent to any other vertex in D. The upper irredundance number IR(G) is the largest cardinality of an irredundant set of G; an IR(G)-set is an irredundant set of cardinality IR(G). The IR-graph of G has the IR(G)-sets as vertex set, and sets A and B are adjacent if and only if B can be obtained from A by exchanging a single vertex of A for an adjacent vertex in B. An IR-tree is an IR-graph that is a tree. We characterize IR-trees of diameter 3 by showing that these graphs are precisely the double stars S(2n,2n), i.e., trees obtained by joining the central vertices of two disjoint stars K_{1,2n}.
Keywords
Cite
@article{arxiv.2104.09004,
title = {Irredundance Trees of Diameter 3},
author = {C. M. Mynhardt and A. Roux},
journal= {arXiv preprint arXiv:2104.09004},
year = {2021}
}
Comments
16 pages, 6 figures