Por Hartry Field (New York University).
Por José Carlos Espírito Santo (Centro de Matemática, Universidade do Minho).
Por Pedro Pinto (Faculdade de Ciências, CMAFcIO, Universidade de Lisboa).
Non-deterministic semantics for non-classical logics: an approach from the perspective of model theory and universal algebra
Por Guilherme Toledo (Universidade Estadual de Campinas).
Por Roberto Giuntini (Università di Cagliari).
Por Abílio Rodrigues (Universidade Federal de Minas Gerais).
Por Cristina Sernadas (Instituto Superior Técnico, CMAFcIO).
Abstract: Some reduction techniques are presented for proving decidability of mathematical theories and of logic problems, along with relevant illustrations.
Por Daniel Graça (Universidade do Algarve).
Por Pedro Filipe (Instituto Superior Técnico, Universidade de Lisboa).
Abstract: The compactness theorem is one of the key ingredients used in Lindstrom's Theorem that characterizes first-order logic and follows directly from Godel's completeness theorem, given the finite nature of proofs. In time, alternative proofs were found that don't require the usage of a formal proof system. In this seminar we will show one of these alternative proofs using ultrafilters and ultraproducts.
Por Cristina Sernadas (Instituto Superior Técnico, Universidade de Lisboa).
Abstract: Some results and reduction techniques for proving decidability of mathematical theories and completeness of logics are presented. The crucial role of the theory of real closed ordered fields is explained. Selected illustrations from Euclidean Geometry to Quantum Logic are discussed.