The computation of the time-varying matrix pseudoinverse has become crucial in recent
years for solving time-varying problems in engineering and science domains. This paper …

The COVID-19 pandemic caused a boom in demand for personal protective equipment, or
so-called “COVID-19 goods”, around the world. We investigate three key sectoral global …

In the first part of the paper we present several proofs of the so-called Sylvester criterion for
quadratic forms; some of the said proofs are short and easy. In the second part of the paper …

The main purpose of the present paper is to give a unified account of the various
characterizations of nonsingular M-matrices and a unified “path” of the mathematical proofs …

The paper is devoted to the existence, uniqueness and nonuniqueness of positive solutions
to nonlinear algebraic systems of equations with positive coefficients. Such systems appear …

We provide a complete study of existence and uniqueness (uniqueness up to multiples in
the case d= 0) of non-negative and non-trivial solutions x for the linear system (I− A) x= d …

Motivated by recent developments in applied dynamic analysis, this paper presents new
sufficient conditions for the existence of a Markov perfect equilibrium in dynamic stochastic …

We give an overview of the various characterizations of irreducibility, reducibility and
primitivity for nonnegative square matrices. Some comments are made for the so-called …

Algebraic systems with positive coefficients appear in several applications. We consider a
family of such systems depending on parameters. Using Brouwer's Theorem, properties of …

Increasing electricity production from renewable energy sources has, by its fluctuating
nature, created the need for more flexible demand side management. How to integrate …