[ES] Durante las primeras décadas del siglo pasado se estudiaron las inversas generalizadas que hoy en día se conocen como inversas generalizadas clásicas. Entre ellas cabe mencionar la inversa de Moore-Penrose (1955) y la inversa de Drazin (1958). Mientras que la inversa de Moore-Penrose se definió originalmente para matrices complejas rectangulares, la inversa de Drazin fue tratada, en un primer momento, únicamente para matrices cuadradas. Más tarde, en 1980, Cline y Greville realizaron la extensión del caso cuadrado al caso rectangular, mediante la consideración de una matriz de ponderación rectangular. Diferentes propiedades, caracterizaciones y aplicaciones fueron obtenidas para estos tipos de inversas generalizadas hasta finales del siglo pasado. En la última década, han aparecido nuevas nociones de inversas generalizadas. La primera de ellas fue la inversa core, introducida en el año 2010 por los autores Baksalary y Trenkler. La misma tuvo una amplia repercusión en la comunidad matemática debido a la sencillez de su definición, a su aplicación en la resolución de algunos sistemas lineales con restricciones que surgen en la teoría de redes eléctricas y también por su conexión con la inversa de Bott- Duffin. Muchos trabajos de investigación han surgido a partir de la inversa core, incluyendo sus extensiones a conjuntos más generales como el álgebra de operadores lineales acotados sobre espacios de Hilbert y/o al ámbito de anillos abstractos. El objetivo principal de esta tesis doctoral es definir y estudiar en profundidad una nueva inversa generalizada para matrices rectangulares, llamada inversa inversa de grupo débil ponderada, la cual extiende al caso rectangular la inversa de grupo débil recientemente definida (para el caso cuadrado) por Wang y Chen. También se considera un amplio estudio de la inversa core-EP ponderada definida por Ferreyra, Levis y Thome en el año 2018, y que extiende al caso rectangular inversa core-EP introducida por Manjunatha-Prasad y Mohana en el año 2014. Para ambas inversas generalizadas se obtienen nuevas propiedades, representaciones, caracterizaciones como así también su relación con otras inversas conocidas en la literatura. Además, se presentan dos algoritmos que permiten realizar un cálculo efectivo de las mismas. / [CA] Durant les primeres dècades del segle passat es van estudiar les inverses generalitzades que hui dia es coneixen com a inverses generalitzades clàssiques. Entre elles cal esmentar la inversa de Moore-Penrose (1955) i la inversa de Drazin (1958). Mentre que la inversa de Moore-Penrose es va definir originalment per a matrius complexes rectangulars, la inversa de Drazin va ser tractada, en un primer moment, únicament per a matrius quadrades. Més tard, en 1980, Cline i Greville van realitzar l'extensió del cas quadrat al cas rectangular, mitjançant la consideració d'una matriu de ponderació rectangular. Diferents propietats, caracteritzacions i aplicacions van ser obtingudes per a aquests tipus d'inverses generalitzades fins a finals del segle passat. En l'última dècada, han aparegut noves nocions d'inverses generalitzades. La primera d'elles va ser la inversa core, introduïda l'any 2010 pels autors Baksalary i Trenkler. La mateixa va tindre una àmplia repercussió en la comunitat matemàtica a causa de la senzillesa de la seua definició, a la seua aplicació en la resolució d'alguns sistemes lineals amb restriccions que sorgeixen en la teoria de xarxes elèctriques i també per la seua connexió amb la inversa de Bott-Duffinn. Molts treballs de recerca han sorgit a partir de la inversa core, incloent les seues extensions a conjunts més generals com l'àlgebra d'operadors lineals delimitats sobre espais de Hilbert i/o a l'àmbit d'anells abstractes. L'objectiu principal d'aquesta tesi doctoral és definir i estudiar en profunditat una nova inversa generalitzada per a matrius rectangulars, anomenada inversa inversa de grup feble ponderada, la qual estén al cas rectangular la inversa de grup feble recentment definida (per al cas quadrat) per Wang i Chen. Tamb é es considera un ampli estudi de la inversa core-EP ponderada definida per Ferreyra, Levis i Thome l'any 2018, i que estén al cas rectangular inversa core-EP introduïda per Manjunatha-Prasad i Mohana l'any 2014. Per a totes dues inverses generalitzades s'obtenen noves propietats, representacions, caracteritzacions com així també la seua relació amb altres inverses conegudes en la literatura. A més, es presenten dos algorismes que permeten realitzar un càlcul efectiu d'aquestes. / [EN] Generalized inverses, known today as Classical Generalized Inverses, were studied during the first decades of the last century. Two important classical generalized inverses are the Moore-Penrose inverse (1955) and the Drazin inverse (1958). The Moore-Penrose inverse was originally defined for complex rectangular matrices. In turn, the Drazin inverse was studied, at first, only for square matrices. It was in 1980 when Cline and Greville extended the case of square matrices to the case of rectangular matrices by considering a weight rectangular matrix. Throughout the entire past century there appeared difierent properties, characterizations and applications of these types of generalized inverses. This last decade gave rise to new notions of generalized inverses. The first of these new notions is known as the core inverse. Core inverses were introduced in 2010 by Baksalary and Trenkler. Their work had a wide repercussion in the mathematical community due to the simplicity of its denition and its application in the solution of some linear systems with restrictions. The core inverse further gain in interest due to their connection to the Bott-Duffin inverse. There is a large body of work on the core inverse, including extensions to more general sets if such as the algebra of bounded linear operators on Hilbert spaces and/or abstract rings. The main goal of this thesis is to define and study in depth a new generalized inverse for rectangular matrices. This new inverse is called weighted weak group inverse (or weighted WG inverse). Weighted WG inverses extend weak group inverse, recently defined for the square case by Wang and Chen, to the rectangular case. We also consider an extensive study of the weighted core-EP inverse. The latter type of inverse was dened by Ferreyra, Levis, and Thome in 2018. This inverse extends the core-EP inverse introduced by Manjunatha- Prasad and Mohana in 2014 to the rectangular case. This thesis presents new properties, representations, characterizations, as well as their relation with other inverses known in the literature are obtained, for weighted WG inverses and weighted core-EP inverse. In addition, the thesis presents two algorithms that allow for an efiective computation weighted WG inverses and weighted core-EP inverse. / Orquera, V. (2022). La inversa core-EP y la inversa de grupo débil para matrices rectangulares [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/185227

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-09-14T18:15:51Z No. of bitstreams: 1 Maria Eliana Santana Da Cruz Silva.pdf: 2630796 bytes, checksum: 59dcb18293cd1765db482b9ff7efb016 (MD5) / Made available in DSpace on 2016-09-14T18:15:51Z (GMT). No. of bitstreams: 1 Maria Eliana Santana Da Cruz Silva.pdf: 2630796 bytes, checksum: 59dcb18293cd1765db482b9ff7efb016 (MD5) Previous issue date: 2016-03-21 / This doctoral dissertation reports an investigation of the conceptions of linear transformation held by teaching certification students in mathematics following a course of linear algebra devised to involve students in the search for elements to build the concept of this mathematical object. The analysis of these conceptions was carried out according to the APOS theory by Dubinsky and Lewin (1986) and Asiala et al. (1996), in articulation with premises of didactic engineering (MACHADO, 2010). The investigation was a qualitative, case-study type, which, according to Bogdan and Biklen (1994) and Lüdke and André (1986), enables the context studied to be investigated and interpreted, given that all qualitative studies seek to portray reality in a more dense fashion and represent the different perspectives present in a given social situation. Centered on this understanding of qualitative research, classes were organized with the aim of actively involving the study participants to facilitate data collection, which was carried out three semesters after the linear algebra course. Premises of didactic engineering were employed to prepare and conduct the activities, which were discussed and solved by paired students. Their interactions were audio recorded and also noted by an observer. The analysis revealed that the subjects paired for the activities experienced different stages in terms of conception (action, process, and object) in most of the activities. We concluded that the students investigated did not always show a conception of object during the activities, but were all able to demonstrate a conception of process for the notion of linear transformation / Esta tese apresenta uma pesquisa que busca investigar as concepções de transformação linear de alunos de uma licenciatura em matemática ao vivenciarem um curso de álgebra linear elaborado com a intenção de envolvê-los na busca de elementos para a construção desse objeto matemático. A análise das concepções se embasou principalmente em partes da teoria APOS, de Dubinsky e Lewin (1986) e Asiala et al. (1996), articulada com alguns pressupostos da engenharia didática (MACHADO, 2010). A pesquisa se caracteriza como qualitativa, abordagem que, segundo Bogdan e Biklen (1994) e Lüdke e André (1986), possibilita investigar e interpretar o contexto investigado, uma vez que todo estudo qualitativo visa retratar a realidade de forma densa, procurando representar as diferentes perspectivas presentes em dada situação social. A partir dessa compreensão de pesquisa qualitativa, foi possível organizar aulas com o objetivo de envolver ativamente os participantes da pesquisa, de forma a facilitar a coleta de dados, que foi realizada após três semestres do curso em questão. Utilizamos pressupostos da engenharia didática na preparação e execução das atividades, discutidas e resolvidas em duplas, atividades essas audiogravadas e descritas por um observador. As análises revelaram que os sujeitos que compuseram as duplas durante a realização das atividades vivenciaram diferentes etapas em termos de concepção (ação, processo e objeto) na maioria das atividades propostas. Concluímos que os sujeitos da pesquisa nem sempre demonstraram uma concepção de objeto no desenvolvimento das atividades, mas todos foram capazes de demonstrar uma concepção de processo da noção de transformação linear

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-09-19T18:15:35Z No. of bitstreams: 1 Eneias de Almeida Prado.pdf: 2836283 bytes, checksum: 5e4837beb1b8460495d29484621fb1da (MD5) / Made available in DSpace on 2016-09-19T18:15:35Z (GMT). No. of bitstreams: 1 Eneias de Almeida Prado.pdf: 2836283 bytes, checksum: 5e4837beb1b8460495d29484621fb1da (MD5) Previous issue date: 2016-04-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study had intended to understand the Linear Algebra, used for teach the Mathematics graduation, with knowledge for the graduation of Mathematics teacher, that will work in Basic Education, and search for elements and possibilities for attribute a new meaning to Linear Algebra in this graduation area, developing a set of knowledge in Linear Algebra, very important for prove the Algebra will be teaching, in Basic Education. The relevancy of research is in the necessity of research the function of academic Mathematics at graduation and be, the Linear Algebra, important at initial graduation of professionals in Mathematics Science area. The theoretical ideas that had used for make the analyzes is related: The initial graduation of teacher, to teach and to learn Linear Algebra and to theoretical aid, advanced thought mathematics, proposed by Dreyfus. So, with a qualitative approach of research, I have analyzes institutional documents of 6 universities, and I have accomplished interviews with 8 teachers. The analysis accomplished show that the Linear Algebra is in the institutional documents researched show to be, independent, of the subject that refer to teaching and learn in Mathematics; but, was possible show elements that may contribute with the professional formation of graduate: to realize that concept has studied by him, is not isolated concepts; make use of the different representation; to explore the concept of definition and the job that practice in Mathematics; to set up with another subject; to explore the truth in Mathematics; to experience another way to valid opinion; to explore questions about the historic moment the have helped the constitution of subject, and deal with Basic Education the light of PMA / Este estudo teve o objetivo de compreender a Álgebra Linear ensinada para a Licenciatura em Matemática como um saber voltado para a formação do professor de Matemática que atuará na Educação Básica e buscar elementos e possibilidades para ressignificar a Álgebra Linear nessa formação, concebendo um conjunto de conhecimentos em Álgebra Linear, necessário para fundamentar a Álgebra a ser ensinada, na Educação Básica. A relevância da pesquisa reside na necessidade de investigar o papel da Matemática acadêmica na licenciatura e ser, a Álgebra Linear, importante na formação inicial de profissionais na área das Ciências Exatas e afins. As ideias teóricas que embasaram as análises estam relacionadas: à formação inicial do professor, ao ensino e à aprendizagem em Álgebra Linear e ao aporte teórico, Pensamento Matemático Avançado – PMA –, proposto por Dreyfus. Assim, com uma abordagem qualitativa de pesquisa, analisei documentos institucionais de seis universidades e realizei entrevistas com oito professores. Para a análise dos dados usei pressupostos de um estudo por saturação. A análise realizada indica que a Álgebra Linear presente nos documentos institucionais investigados mostra ser planejada, independentemente, das disciplinas que se referem ao ensino e à aprendizagem em Matemática; por outro lado, foi possível evidenciar elementos que podem contribuir com a formação profissional do licenciando: perceber que conceitos estudados por ele, não são conceitos isolados; fazer uso de diferentes representações; explorar o conceito de definição e o papel o qual exerce em Matemática; estabelecer relações com outras disciplinas; explorar o critério de verdade em Matemática; vivenciar diversas formas de validar conjecturas; explorar questões relacionadas ao momento histórico que possibilitou a constituição da disciplina, além de abordar noções de Matemática da Educação Básica à luz do PMA

A graph is a mathematical structure for modelling the pairwise relations between objects. This thesis studies two types of graphs, namely, similarity-based graphs and evolving graphs. We look at ways to traverse an evolving graph. In particular, we examine the influence of temporal information on node centrality. In the process, we develop EvolvingGraphs.jl, a software package for analyzing time-dependent networks. We develop Etymo, a search system for discovering interesting research papers. Etymo utilizes both similarity-based graphs and evolving graphs to build a knowledge graph of research articles in order to help users to track the development of ideas. We construct content similarity-based graphs using the full text of research papers. And we extract key concepts from research papers and exploit the temporal information in research papers to construct a concepts evolving graph.

Cette thèse présente une vision unifiée de plusieurs méthodes de décomposition de domaine : celles avec recouvrement, dites de Schwarz, et celles basées sur des compléments de Schur, dites de sous-structuration. Il est ainsi possible de changer de méthodes de manière abstraite et de construire différents préconditionneurs pour accélérer la résolution de grands systèmes linéaires creux par des méthodes itératives. On rencontre régulièrement ce type de systèmes dans des problèmes industriels ou scientifiques après discrétisation de modèles continus. Bien que de tels préconditionneurs exposent naturellement de bonnes propriétés de parallélisme sur les architectures distribuées, ils peuvent s’avérer être peu performants numériquement pour des décompositions complexes ou des problèmes physiques multi-échelles. On peut pallier ces défauts de robustesse en calculant de façon concurrente des problèmes locaux creux ou denses aux valeurs propres généralisées. D’aucuns peuvent alors identifier des modes qui perturbent la convergence des méthodes itératives sous-jacentes a priori. En utilisant ces modes, il est alors possible de définir des opérateurs de projection qui utilisent un problème dit grossier. L’utilisation de ces outils auxiliaires règle généralement les problèmes sus-cités, mais tend à diminuer les performances algorithmiques des préconditionneurs. Dans ce manuscrit, on montre en trois points quela nouvelle construction développée est performante : 1) grâce à des essais numériques à très grande échelle sur Curie—un supercalculateur européen, puis en le comparant à des solveurs de pointe 2) multi-grilles et 3) directs. / This thesis introduces a unified framework for various domain decomposition methods:those with overlap, so-called Schwarz methods, and those based on Schur complements,so-called substructuring methods. It is then possible to switch with a high-level of abstractionbetween methods and to build different preconditioners to accelerate the iterativesolution of large sparse linear systems. Such systems are frequently encountered in industrialor scientific problems after discretization of continuous models. Even though thesepreconditioners naturally exhibit good parallelism properties on distributed architectures,they can prove inadequate numerical performance for complex decompositions or multiscalephysics. This lack of robustness may be alleviated by concurrently solving sparse ordense local generalized eigenvalue problems, thus identifying modes that hinder the convergenceof the underlying iterative methods a priori. Using these modes, it is then possibleto define projection operators based on what is usually referred to as a coarse solver. Theseauxiliary tools tend to solve the aforementioned issues, but typically decrease the parallelefficiency of the preconditioners. In this dissertation, it is shown in three points thatthe newly developed construction is efficient: 1) by performing large-scale numerical experimentson Curie—a European supercomputer, and by comparing it with state of the art2) multigrid and 3) direct solvers.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-01-26T09:20:52Z No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-30T10:25:56Z (GMT) No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-30T10:25:56Z (GMT). No. of bitstreams: 2 Dissertação - Jânio Alves dos Santos Júnior - 2016.pdf: 3798217 bytes, checksum: c2acd93260ead52c126f4b37d994825f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work aims to study some topics of graph theory in order to solve some problems. In order to complement, we approached a light study of matrices, eigenvalues and eigenvectors. The first problem is known as Königsberg Bridge Problem, where this was considered the problem that gave rise to the study on graphs. The House Problem is a joke, which shows us several propositions about planar and bipartite graphs. Some models we can relate graphs, such as we can observe in the problem of cannibals and in the game of chess. Finally, we will work with applications in the adjacency matrix as in the Problem of the Condominium of Farms and in the Number of Possible Paths in a graph, where we will work with geometric figures, apparently resolving a counting problem using eigenvalues and graph. As a methodological support will be approached Linear Algebra. / O objetivo deste trabalho é estudar alguns tópicos da teoria de grafos com o intuito de resolver alguns problemas. Para complementar, abordamos um leve estudo de matrizes, autovalores e autovetores. O primeiro problema é conhecido como o Problema da Ponte de Königsberg, onde tal, foi considerado o problema que deu origem ao estudo sobre grafos. O Problema das Casas que é uma brincadeira, que nos mostra várias proposições sobre grafos planares e bipartidos. Alguns modelos que podemos relacionar grafos, tais como veremos no problema dos canibais e no jogo de xadrez. Por fim, trabalharemos com aplicações na matriz de adjacência como no problema do Condomínio de Chácaras e no Número de Caminhos Possíveis em um Grafo, onde trabalharemos com figuras geométricas, resolvendo aparentemente um problema de contagem, utilizando autovalores e grafos. Como suporte metodológico será abordado Álgebra Linear.

The focus of this dissertation is the advancement of theory and computation related to exact precision mathematical programming. Optimization software based on floating-point arithmetic can return suboptimal or incorrect resulting because of round-off errors or the use of numerical tolerances. Exact or correct results are necessary for some applications. Implementing software entirely in rational arithmetic can be prohibitively slow. A viable alternative is the use of hybrid methods that use fast numerical computation to obtain approximate results that are then verified or corrected with safe or exact computation. We study fast methods for sparse exact rational linear algebra, which arises as a bottleneck when solving linear programming problems exactly. Output sensitive methods for exact linear algebra are studied. Finally, a new method for computing valid linear programming bounds is introduced and proven effective as a subroutine for solving mixed-integer linear programming problems exactly. Extensive computational results are presented for each topic.

This thesis focus on memory-aware algorithms tailored for hierarchical memory architectures, found for instance within multicore processors. We first study the matrix product on multicore architectures. We model such a processor, and derive lower bounds on the communication volume. We introduce three ad hoc algorithms, and experimentally assess their performance.We then target a more complex operation: the QR factorization of tall matrices. We revisit existing algorithms to better exploit the parallelism of multicore processors. We thus study the critical paths of many algorithms, prove some of them to be asymptotically optimal, and assess their performance.In the next study, we focus on scheduling streaming applications onto a heterogeneous multicore platform, the QS 22. We introduce a model of the platform and use steady-state scheduling techniques so as to maximize the throughput. We present a mixed integer programming approach that computes an optimal solution, and propose simpler heuristics. We then focus on minimizing the amount of required memory for tree-shaped workflows, and target a classical two-level memory system. I/O represent transfers from a memory to the other. We propose a new exact algorithm, and show that there exist trees where postorder traversals are arbitrarily bad. We then study the problem of minimizing the I/O volume for a given memory, show that it is NP-hard, and provide a set of heuristics.Finally, we compare archival policies for BLUE WATERS. We introduce two archival policies and adapt the well known RAIT strategy. We provide a model of the tape storage platform, and use it to assess the performance of the three policies through simulation.

Designing efficient code in practice for a given computation is a hard task. In this thesis, we tackle this issue in two different situations. The first part of the thesis introduces some algorithmic improvements in structured linear algebra. We first show how to extend an algorithm by Cardinal for inverting Cauchy-like matrices to the other common structures. This approach, which mainly relies on products of the type "structured matrix × matrix", leads to a theoretical speed-up of a factor up to 7 that we also observe in practice. Then, we extend some works on Toeplitz-like matrices and prove that, for any of the common structures, the product of an n×n structured matrix of displacement rank α by an n×α matrix can be computed in Õ(α^(ω-1)n). This leads to direct inversion algorithms in Õ(α^(ω-1)n) , that do not rely on a reduction to the Toeplitz-like case. The second part of the thesis deals with the implementation of arithmetic expressions. This topic raises several issues like finding the minimum number of operations, and maximizing the speed or the accuracy when using some finite-precision arithmetic. Making use of the inductive nature of arithmetic expressions enables the design of algorithms that help to answer such questions. We thus present a set of algorithms for generating evaluation schemes, counting them, and optimizing them according to one or several criteria. These algorithms are part of a library that we have developed and used, among other things, in order to decrease the running time of a code generator for a mathematical library, and to study optimality issues about the evaluation of a small degree polynomial with scalar coefficients at a matrix point.

In mathematics the parameter is used as a special kind of a variable. The classification of the terms \"variable\" and \"parameter\" is often done by intuition and changes due to different situations and needs. The history of mathematics shows that these two terms represent the same abstract object in mathematics. In today´s mathematics, compared to variables, the parameter is declared as an unknown constant measure. This interpretation of parameters can be used in set theory for describing sets with an infinite number of elements. Due to this perspective the structure of vector spaces can be developed as a special structured set theory. Further, the concept of parameters can be seen as a model for developing mathematics education in linear algebra.