Preface

Mauricio Ayala-Rincón, Elaine Pimentel, Fairouz Kamareddine
2011 Theoretical Computer Science  
Preface This special issue contains extended versions of selected works and invited speaker's contributions presented at the Third and Fourth Workshops on Logical and Semantical Frameworks with Applications (LSFA 2008+09). The workshops were held in Ouro Preto and Brasília, Brazil, in August 2008 and August 2009, as affiliated events of the Brazilian Symposium in Formal Methods (SBFM 2008) and of the Federated Conference on Rewriting, Deduction and Programming (RDP 2009). Logical and Semantic
more » ... ameworks with Applications is a workshop series which is dedicated to bringing together theoreticians and practitioners in the field of computational logics and semantics to promote new techniques and results, from the theoretical side, and feedback on the implementation and the use of such techniques and results, from the practical side. The papers were carefully reviewed by specialists, including members of the LSFA 2008 and 2009 Program Committees as well as additional experts in order to reach the quality standards of TCS publications, for which the guest editors are grateful. In the following, a short introduction is given to each of the six papers included in this volume. Camilo Rocha, César Muñoz and Gilles Dowek, in "A Formal Library of Set Relations and Its Application to Synchronous Languages", provide a library of set relations suitable for the definition of synchronous programming languages. The authors state that several synchronous languages such as Esterel, Lustre, and Signal lack a formal framework for the definition of their operational semantics that is general (or formal) enough that properties of a binary set relation such as the asynchronicity, synchronicity, parallelism, and compositionality of that set relation can be studied. The authors then illustrate the applicability of these set relations and their properties by defining the semantics of PLEXIL in rewriting logic, a programming language recently used for defining operational semantics of several programming languages. For the definition of the semantics of PLEXIL in rewriting logic and, more concretely, in the Maude implementation, the authors need a serialization procedure, that is, a procedure for describing a synchronous set relation in terms of an asynchronous set relation. This procedure is a cornerstone of this paper, and its correctness is proved. Delia Kesner and Fabien Renaud, in "A Prismoid Framework for Languages with Resources", describe a family of lambdacalculi with explicit substitutions, explicit copy, and explicit erase. Each member of the family is characterized by a combination of zero or more of these three features. In particular, the usual lambda-calculus with implicit substitutions, copy, and erase is a member of the family as well as the lambda-calculus in which all the three mechanisms are explicit. These two calculi have been the subject of previous research, and some of the other calculi in the family are defined in this paper for the first time. The calculi of this family are organized as vertices of a prismoid, which is an interesting organization that helps one to see the relationships between them. The main results are general proofs of confluence for all the calculi, and preservation of strong normalization. Simple typed versions of the calculi for which strong normalization is proved are also presented. The paper by Francicleber Ferreira and Ana Teresa Martins, "Recursive Definitions and Fixed-Points on Well-Founded Structures", studies the problem of whether Beth's Definability Theorem (BDT) holds for least fixed point (LFP) logic. A theory * Corresponding editor. Tel.: +55 61 3307 2441x2442, +55 61 3107 6453; fax: +55 61 3273 2737.
doi:10.1016/j.tcs.2011.06.002 fatcat:nkejks5grzhv7hpykplh4f4mhu