This volume was motivated by the Year of Prolog initiative, launched to celebrate the 50th anniversary of the emergence of Prolog through the work of Alain Colmerauer’s team in Marseille. The volume editors, authors, and scientific advisors and reviewers have been the leading researchers and programmers in this field over decades, and the book represents an excellent overview of the field, its successes, and its future.After a first chapter that gently introduces the Prolog programming language using examples, the next 7 papers discuss general views of the language, possible extensions for the future, and how Prolog can generally be used to solve problems; the next 5 papers explore ideas and experiences of teaching Prolog programming and then 2 papers discuss technology that has been developed for help in that teaching; the next 3 papers describe new languages based on Prolog which show future directions for logic programming; the next 5 chapters explain the applications that were the finalists for the 2022 Alain Colmerauer Prize; and the final 8 papers describe applications developed using the Prolog language, demonstrating the language’s range.

This book constitutes the thoroughly refereed post-conference proceedings of the 26th International Symposium on Logic-Based Program Synthesis and Transformation, LOPSTR 2016, held in Edinburgh, UK, in September 2016. The 20 revised full papers presented together with the abstracts of 3 invited talks were carefully reviewed and selected from 38 submissions. The aim of the LOPSTR series is to stimulate and promote international research and collaboration on logic-based program development. LOPSTR is open to contributions in all aspects of logic-based program development, all stages of the software life cycle, and issues of both programming-in-the-small and programming-in-the-large. LOPSTR traditionally solicits contributions, in any language paradigm, in the areas of synthesis, specification, transformation, analysis and verification, specialization, testing and certification, composition, program/model manipulation, optimization, transformational techniques in SE, inversion, applications, and tools.