A note on universally optimal matrices and field independence of the minimum rank of a graph
Journal
Linear Algebra and Its Applications
Journal Volume
433
Journal Issue
3
Pages
585-594
Date Issued
2010
Author(s)
Abstract
For a simple graph G on n vertices, the minimum rank of G over a field F, written as mrF (G), is defined to be the smallest possible rank among all n × n symmetric matrices over F whose (i, j)th entry (for i ≠ j) is nonzero whenever {i, j} is an edge in G and is zero otherwise. A symmetric integer matrix A such that every off-diagonal entry is 0, 1, or - 1 is called a universally optimal matrix if, for all fields F, the rank of A over F is the minimum rank of the graph of A over F. Recently, Dealba et al. [L.M. Dealba, J. Grout, L. Hogben, R. Mikkelson, K. Rasmussen, Universally optimal matrices and field independence of the minimum rank of a graph, Electron. J. Linear Algebra 18 (2009) 403-419] initiated the study of universally optimal matrices and established field independence or dependence of minimum rank for some families of graphs. In the present paper, more results on universally optimal matrices and field independence or dependence of the minimum rank of a graph are presented, and some results of Dealba et al. [5] are improved. © 2010 Elsevier Inc. All rights reserved.
Type
journal article