2010/06/04 by Friedland, Shmuel, Loewy, Raphael · 1 citation
#05AC50 #11T99 #15A03 #Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1006.0770
In this paper we deal with two aspects of the minimum rank of a simple undirected graph G on n vertices over a finite field \FFq with q elements, which is denoted by \mr(\FFq,G). In the first part of this paper we show that the average minimum rank of simple undirected labeled graphs on n vertices over \FF2 is (1-εn)n, were limn→∞ εn=0. In the second part of this paper we assume that G contains a clique Kk on k-vertices. We show that if q is not a prime then \mr(\FFq,G)≤ n-k+1 for 4≤ k≤ n-1 and n≥ 5. It is known that \mr(\FFq,G)≤ 3 for k=n-2, n≥ 4 and q≥ 4. We show that for k=n-2 and each n≥ 10 there exists a graph G such that \mr(\FF3,G)>3. For k=n-3, n≥ 5 and q≥ 4 we show that \mr(\FFq,G)≤ 4.