Encontrados 24 documentos, a visualizar página 1 de 3
The Moore-Penrose inverse of a companion matrix
Patrício, PedroNecessary and sufficient conditions are given for the Moore-Penrose inverse of a companion matrix over an arbitrary ring to exist.
The inverse along a lower triangular matrix
Mary, Xavier; Patrício, PedroIn this paper, we investigate the recently defined notion of inverse along an element in the context of matrices over a ring. Precisely, we study the inverse of a matrix along a lower triangular matrix, under some conditions.
The (2,2,0) drazin inverse problem
Patrício, Pedro; Hartwig, Robert E.We consider the additive Drazin problem and we study the existence of the Drazin inverse of a two by two matrix with zero (2,2) entry.
Contribuição para uma proposta de qualificação das áreas urbanas de génese ilegal
Patrício, Pedro Miguel MatosDissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Civil – Perfil Construção ; As áreas urbanas de génese ilegal, denominadas de AUGI, surgiram à margem da lei principalmente no inicio da década de 60, como um fenómeno que se foi expandindo de uma forma abrupta essencialmente nas periferias das grandes áreas metropolitana...
Moore-Penrose invertibility in involutory rings : the case aa+=bb+
Patrício, Pedro; Araújo, C. MendesIn this article, we consider Moore-Penrose invertibility in rings with a general involution. Given two von Neumann regular elements a, b in a general ring with an arbitrary involution, we aim to give necessary and sufficient conditions to aa† = bb†. As a special case, EP elements are considered.
Generalized inverses of a sum in rings
Castro-González, N.; Araújo, C. Mendes; Patrício, PedroDocumento submetido para revisão pelos pares. A publicar em "Bulletin of the Australian Mathematical Society". ISSN 0004-9727. 82:1 (2010) 156-164. ; We study properties of the Drazin index of regular elements in a ring with a unity 1. We give expressions for generalized inverses of 1 − ba in terms of generalized inverses of 1 − ab. In our development we prove that the Drazin index of 1 − ba is equal to the Dr...
The (2,2,0) group inverse problem
Patrício, Pedro; Hartwig, Robert E.We characterize the existence of the group inverse of a two by two matrix with zero (2,2) entry, over a ring by means of the existence of the inverse of a suitable function of the other three entries. Some special cases are derived.
The link between regularity and strong-pi-regularity
Patrício, Pedro; Hartwig, Robert E.It is shown that if all powers of a ring element $a$ are regular, then $a$ will be strongly-pi-regular exactly when a suitable word in the powers of $a$ and their inner inverses is a unit.
Modelos de programação linear inteira para problemas de dimensionamento e engen...
Patrício, Pedro Ferrão, 1977-Tese de doutoramento, Estatística e Investigação Operacional (Optimização), 2009, Universidade de Lisboa, Faculdade de Ciências ; In this thesis, we develop Integer Linear Programming models to address network dimensioning and traffic engineering problems in telecommunications networks. Given the ever increasing need for reliable and delay sensitive services, our main focus is on survivability and delay constr...
Some additive results on Drazin Inverses
Patrício, Pedro; Hartwig, Robert E.In this paper, some additive results on Drazin inverse of a sum of Drazin invertible elements are derived. Some converse results are also presented.
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