LINEAR ALGEBRA AND ITS APPLICATIONS, vol.493, pp.1-13, 2016 (SCI-Expanded)
Let K-n, be the set of all n x n lower triangular (0, 1)-matrices with each diagonal element equal to 1, L-n = {YYT : Y is an element of K-n} and let c(n) be the minimum of the smallest eigenvalue of YYT as Y goes through K-n. The Ilmonen-Haukkanen-Merikoski conjecture (the IHM conjecture) states that c(n), is equal to the smallest eigenvalue of Y0Y0T, where Y-0 is an element of K-n with (Y-0)(ij) = 1-(-1)(1+j)/2 for i > j. In this paper, we present a proof of this conjecture. In our proof we use an inequality for spectral radii of nonnegative matrices. (C) 2015 Elsevier Inc. All rights reserved.