The Hadamard product and related dilations
The higher rank numerical range of nonnegative matrices
In this article the rank-k numerical range ∧k (A) of an entrywise nonnegative matrix A is investigated. Extending the notion of elements of maximum modulus in ∧k (A), we examine their location on the complex plane. Further, an application of this theory to ∧k (L(λ)) of a Perron polynomial L(λ) is elaborated via its companion matrix C L.
The minimum, diagonal element of a positive matrix
Properties of the minimum diagonal element of a positive matrix are exploited to obtain new bounds on the eigenvalues thus exhibiting a spectral bias along the positive real axis familiar in Perron-Frobenius theory.
The nonnegative -matrix completion problem.
The -matrix completion problem.
The -matrix completion problem.
The semigroup of fully indecomposable relations and Hall relations
The structure of linear operators strongly preserving majorizations of matrices.
The theory and applications of complex matrix scalings
We generalize the theory of positive diagonal scalings of real positive definite matrices to complex diagonal scalings of complex positive definite matrices. A matrix A is a diagonal scaling of a positive definite matrix M if there exists an invertible complex diagonal matrix D such that A = D*MD and where every row and every column of A sums to one. We look at some of the key properties of complex diagonal scalings and we conjecture that every n by n positive definite matrix has at most 2n−1 scalings...
The third smallest eigenvalue of the Laplacian matrix.
The weak Hawkins-Simon condition.
The (weakly) sign symmetric -matrix completion problems.
Theorems of the alternative for cones and Lyapunov regularity of matrices
Standard facts about separating linear functionals will be used to determine how two cones and and their duals and may overlap. When is linear and and are cones, these results will be applied to and , giving a unified treatment of several theorems of the alternate which explain when contains an interior point of . The case when is the space of Hermitian matrices, is the positive semidefinite matrices, and yields new and known results about the existence of block diagonal...
Two characterizations of inverse-positive matrices: the Hawkins-Simon condition and the Le Chatelier-Braun principle.
Universal bounds for positive matrix semigroups
We show that any compact semigroup of positive n × n matrices is similar (via a positive diagonal similarity) to a semigroup bounded by √n. We give examples to show this bound is best possible. We also consider the effect of additional conditions on the semigroup and obtain improved bounds in some cases.
Upper bound for the non-maximal eigenvalues of irreducible nonnegative matrices
We present a lower and an upper bound for the second smallest eigenvalue of Laplacian matrices in terms of the averaged minimal cut of weighted graphs. This is used to obtain an upper bound for the real parts of the non-maximal eigenvalues of irreducible nonnegative matrices. The result can be applied to Markov chains.
Upper bounds on certain functionals defined on groups of linear operators.
Variational characterizations of the sign-real and the sign-complex spectral radius.
Vorzeichenstabile Differenzenverfahren für parabolische Anfangsrandwertaufgaben.
Weighted trace inequalities of monotonicity.