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An improvement of an inequality of Fiedler leading to a new conjecture on nonnegative matrices

Assaf GoldbergerNeumann, Michael — 2004

Czechoslovak Mathematical Journal

Suppose that A is an n × n nonnegative matrix whose eigenvalues are λ = ρ ( A ) , λ 2 , ... , λ n . Fiedler and others have shown that det ( λ I - A ) λ n - ρ n , for all λ > ρ , with equality for any such λ if and only if A is the simple cycle matrix. Let a i be the signed sum of the determinants of the principal submatrices of A of order i × i , i = 1 , ... , n - 1 . We use similar techniques to Fiedler to show that Fiedler’s inequality can be strengthened to: det ( λ I - A ) + i = 1 n - 1 ρ n - 2 i | a i | ( λ - ρ ) i λ n - ρ n , for all λ ρ . We use this inequality to derive the inequality that: 2 n ( ρ - λ i ) ρ n - 2 i = 2 n ( ρ - λ i ) . In the spirit of a celebrated conjecture due to Boyle-Handelman,...

On a bound on algebraic connectivity: the case of equality

Stephen J. KirklandNeumann, MichaelBryan L. Shader — 1998

Czechoslovak Mathematical Journal

In a recent paper the authors proposed a lower bound on 1 - λ i , where λ i , λ i 1 , is an eigenvalue of a transition matrix T of an ergodic Markov chain. The bound, which involved the group inverse of I - T , was derived from a more general bound, due to Bauer, Deutsch, and Stoer, on the eigenvalues of a stochastic matrix other than its constant row sum. Here we adapt the bound to give a lower bound on the algebraic connectivity of an undirected graph, but principally consider the case of equality in the bound when...

Bounds on the subdominant eigenvalue involving group inverses with applications to graphs

Stephen J. KirklandNeumann, MichaelBryan L. Shader — 1998

Czechoslovak Mathematical Journal

Let A be an n × n symmetric, irreducible, and nonnegative matrix whose eigenvalues are λ 1 > λ 2 ... λ n . In this paper we derive several lower and upper bounds, in particular on λ 2 and λ n , but also, indirectly, on μ = max 2 i n | λ i | . The bounds are in terms of the diagonal entries of the group generalized inverse, Q # , of the singular and irreducible M-matrix Q = λ 1 I - A . Our starting point is a spectral resolution for Q # . We consider the case of equality in some of these inequalities and we apply our results to the algebraic connectivity of undirected...

A central limit theorem for triangular arrays of weakly dependent random variables, with applications in statistics

Michael H. Neumann — 2013

ESAIM: Probability and Statistics

We derive a central limit theorem for triangular arrays of possibly nonstationary random variables satisfying a condition of weak dependence in the sense of Doukhan and Louhichi [84 (1999) 313–342]. The proof uses a new variant of the Lindeberg method: the behavior of the partial sums is compared to that of partial sums of Gaussian random variables. We also discuss a few applications in statistics which show that our central limit theorem is tailor-made for statistics of different type.

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