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Elsa Carvalho's PhD Public Defense
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Elsa Carvalho's PhD Public Defense
The public defense of Elsa Carvalho's PhD Thesis will take place on Monday, November 26th, at 10:00 in Sala de Actos (Ed IV) of FCT/UNL.
The jury has the following composition:
Alexandre Goldsztejn (U. Nantes) - main examiner
Djamila Sam-Haroud (EPFL) - main examiner
Ana Paula Tomás (U. Porto)
Inês Lynce (IST)
Ludwig Krippahl (UNL)
Jorge Cruz (UNL) - Elsa's co-supervisor
Pedro Barahona (UNL) - Elsa's co-supervisor
Title: Probabilistic Constraint Reasoning
Abstract:
The continuous constraint paradigm has been often used to model safe reasoning in applications where uncertainty arises. Constraint propagation propagates intervals of uncertainty among the variables of the problem, eliminating values that do not belong to any solution. However, constraint programming is very conservative: if initial intervals are wide (reflecting large uncertainty), the obtained safe enclosure of all consistent scenarios may be inadequately wide for decision support. Since all scenarios are considered equally likely, insufficient pruning leads to great inefficiency if some costly decisions may be justified by very unlikely scenarios. Even when probabilistic information is available for the variables of the problem, the continuous constraint paradigm is unable to
incorporate and reason with such information. Therefore, it is incapable of distinguish between different scenarios, based on their likelihoods.
This thesis presents a probabilistic continuous constraint paradigm that associates a probabilistic space to the variables of the problem, enabling probabilistic reasoning to complement the underlying constraint reasoning. Such reasoning is used to address probabilistic queries and requires the computation of multi-dimensional integrals on possibly non linear integration regions. Suitable algorithms for such queries are developed, using safe or approximate integration techniques and relying on methods from continuous constraint programming in order to compute safe covers of the integration region.
The thesis illustrates the adequacy of the probabilistic continuous constraint framework for decision support in nonlinear continuous problems with uncertain information, namely on inverse and reliability problems, two different types of engineering problems where the developed framework is particularly adequate to support decision makers.
Tuesday, 20th of November 2012
Departamento de Informática, FCT/UNL
Quinta da Torre 2829-516 CAPARICA - Portugal
Tel. (+351) 21 294 8536 FAX (+351) 21 294 8541
