This book constitutes the thoroughly refereed post-conference proceedings of the 20th International Workshop on Algebraic Development Techniques, WADT 2010, held in July 2010 in Etelsen, Germany. The 15 revised papers presented were carefully reviewed and selected from 32 presentations. The workshop deals with the following topics: foundations of algebraic specification; other approaches to formal specification including process calculi and models of concurrent, distributed and mobile computing; specification languages, methods, and environments; semantics of conceptual modeling methods and techniques; model-driven development; graph transformations, term rewriting and proof systems; integration of formal specification techniques; formal testing and quality assurance validation, and verification.

A double-pronged approach makes this book an extremely useful addition to the literature on this highly relevant contemporary topic. Addressing two basic areas of application for algebras and coalgebras as mathematical objects as well as in the context of their application in computer science the papers cover topics such as abstract models and logics, specialised models and calculi, algebraic and coalgebraic semantics, and system specification and verification. The book is the refereed proceedings of the second CALCO conference, held in August 2007 in Norway.