This volume contains the proceedings of the 21st International Conference on Logic Programming which was held in Sitges (Barcelona), Spain, from October 2nd to 5th, 2005. The conference was colocated with the International Conf- ence on ConstraintProgramming(CP 2005)and the following 6 post-conference workshops: - CICLOPS 2005: Colloquium on Implementation of Constraint and Logic Programming Systems - CSLP 2005: Constraint Solving and Language Processing - WCB 2005: Constraint Based Methods for Bioinformatics - WLPE 2005: Logic-Based Methods in Programming Environments - MoVeLog 2005: Mobile Code Safety and Program Veri?cation Using C- putational Logic Tools - CHR 2005: Constraint Handling Rules The conferencecoincided with a solareclipse, whichoccurredon October 3rd and was visible in Sitges. No conference activities were scheduled at the time of the eclipse to allow delegates to view this extraordinary astronomical event. Since the ?rst conference that was held in Marseilles in 1982, ICLP has been the premier international conference for presenting research in logic progr- ming. In this edition of the conference, extra attention was given to novel - plications of logic programming and to work providing novel integrations of di?erent areas. Colocation with CP 2005 further reinforced these themes, as it provided an opportunity for the exchange of ideas and cross-fertilization among two areaswhich havecommon roots. ICLP 2005and CP 2005sharedthe invited speakers to underscore this e?ort. ICLP 2005 broke new ground by holding a doctoral consortium for the ?rst time in the ICLP series of conference.

This textbook is a thorough, up-to-date introduction to the principles and techniques that guide the design and implementation of modern programming languages. The goal of the book is to provide the basis for a critical understanding of most modern programming languages. Thus, rather than focusing on a specific language, the book identifies the most important principles shared by large classes of languages. The notion of ‘abstract machine’ is a unifying concept that helps to maintain an accurate and elementary treatment. The book introduces, analyses in depth, and compares the imperative, object-oriented, functional, logic, concurrent, constraint-based, and service-oriented programming paradigms. All material coming from the first English edition has been updated and extended, clarifying some tricky points, and discussing newer programming languages. This second edition contains new chapters dedicated to constraint, concurrent, and service-oriented programming. Topics and features: Requires familiarity with one programming language is a prerequisite Provides a chapter on history offering context for most of the constructs in use today Presents an elementary account of semantical approaches and of computability Introduces new examples in modern programming languages like Python or Scala Offers a chapter that opens a perspective on applications in artificial intelligence Conceived as a university textbook, this unique volume will also be suitable for IT specialists who want to deepen their knowledge of the mechanisms behind the languages they use. The choice of themes and the presentation style are largely influenced by the experience of teaching the content as part of a bachelor's degree in computer science.

This book constitutes the thoroughly refereed post-conference proceedings of the 29th International Symposium on Logic-Based Program Synthesis and Transformation, LOPSTR 2019, held in Porto, Portugal, in October 2019. The 15 revised full papers were carefully reviewed and selected from 32 submissions. In addition to the 15 papers, this volume includes 2 invited papers. The symposium cover all aspects of logic-based program development, stages of the software life cycle, and issues of both programming-in-the-small and programming-in-the-large. This year LOPSTR extends its traditional topics to include also logic-based program development based on integration of sub-symbolic and symbolic models, on machine learning techniques and on differential semantics. The papers are grouped into the following topics: static analysis, program synthesis, constraints and unification, debugging and verification, and program transformation.

With great pleasure, I accepted the invitation extended to me to write these few lines of Foreword. I accepted for at least two reasons. The ?rst is that the request came to me from two colleagues for whom I have always had the greatest regard, starting from the time when I ?rst knew and appreciated them as students and as young researchers. The second reason is that the text by Gabbrielli and Martini is very near to the book that I would have liked to have written but, for various reasons, never have. In particular, theapproachadoptedinthisbookistheonewhichImyselfhavefollowed when organising the various courses on programming languages I have taught for almost thirty years at different levels under various titles. The approach, summarised in 2 words, is that of introducing the general concepts (either using linguistic mechanisms or the implementation structures corresponding to them) in a manner that is independent of any speci?c language; once this is done, "real languages" are introduced. This is the only approach that allows one to - veal similarities between apparently quite different languages (and also between paradigms). At the same time, it makes the task of learning different languages e- ier. In my experience as a lecturer, ex-students recall the principles learned in the course even after many years; they still appreciate the approach which allowed them to adapt to technological developments without too much dif?culty.