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Methods in optimization and feasibility for inverse problems and tomography

Grant number: 13/19504-9
Support Opportunities:Scholarships in Brazil - Post-Doctoral
Start date: February 01, 2014
End date: January 31, 2016
Field of knowledge:Physical Sciences and Mathematics - Mathematics - Applied Mathematics
Principal Investigator:Alvaro Rodolfo de Pierro
Grantee:Daniel Reem
Host Institution: Instituto de Ciências Matemáticas e de Computação (ICMC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Many Inverse Problems, especially in emission and X rays computed tomography, are modeled by large scale systems of linear equations that give rise to ill conditioned mathematical problems. In order to find a stable solution it is necessary to add information not contained in the equations. All this information is used through different models where either an optimization or a feasibility problem should be solved. Also, this generates the necessity of studying specific algorithms for this type of mathematical problems as well as the study of the parameters appearing in those algorithms. In this project we propose to study several open problems and theoretical aspects of these algorithms and models. We will study the relationship between the Douglas-Rachford method and relaxed subgradient as well as the acceleration proposed by Nesterov-Beck-Teboulle. Also we will study the possibility of eliminating the underrelaxation parameters analyzing the asymptotic convergence properties. We will analyze the possibility of obtaining a unified theory for the set of divergence measures, like Kullback-Leibler, that are used to measure equations consistency that models the information about noise in data in Inverse Problems.

News published in Agência FAPESP Newsletter about the scholarship:
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Scientific publications (4)
(The scientific publications listed on this page originate from the Web of Science or SciELO databases. Their authors have cited FAPESP grant or fellowship project numbers awarded to Principal Investigators or Fellowship Recipients, whether or not they are among the authors. This information is collected automatically and retrieved directly from those bibliometric databases.)
REEM, DANIEL; REICH, SIMEON; DE PIERRO, ALVARO. Re-examination of Bregman functions and new properties of their divergences. OPTIMIZATION, v. 68, n. 1, SI, p. 279-348, . (13/19504-9)
REEM, DANIEL; REICH, SIMEON; DE PIERRO, ALVARO. A Telescopic Bregmanian Proximal Gradient Method Without the Global Lipschitz Continuity Assumption. JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS, v. 182, n. 3, p. 851-884, . (13/19504-9)
REEM, DANIEL; REICH, SIMEON; DE PIERRO, ALVARO. Re-examination of Bregman functions and new properties of their divergences. OPTIMIZATION, v. 68, n. 1, p. 70-pg., . (13/19504-9)