This work, a tribute to renowned researcher Robert Paige, is a collection of revised papers published in his honor in the Higher-Order and Symbolic Computation Journal in 2003 and 2005. Among them there are two key papers: a retrospective view of his research lines, and a proposal for future studies in the area of the automatic program derivation. The book also includes some papers by members of the IFIP Working Group 2.1 of which Bob was an active member.

Automatic Program Development is a tribute to Robert Paige (1947-1999), our accomplished and respected colleague, and moreover our good friend, whose untimely passing was a loss to our academic and research community. We have collected the revised, updated versions of the papers published in his honor in the Higher-Order and Symbolic Computation Journal in the years 2003 and 2005.

Among them there are two papers by Bob: (i) a retrospective view of his research lines, and (ii) a proposal for future studies in the area of the automatic program derivation. The book also includes some papers by members of the IFIP Working Group 2.1 of which Bob was an active member. All papers are related to some of the research interests of Bob and, in particular, to the transformational development of programs and their algorithmic derivation from formal specifications. Automatic Program Development offers a renewed stimulus for continuing and deepening Bob's research visions.

A familiar touch is given to the book by some pictures kindly provided to us by his wife Nieba, the personal recollections of his brother Gary and some of his colleagues and friends."

This book constitutes the proceedings of the 22nd International Conference on Verification, Model Checking, and Abstract Interpretation, VMCAI 2021, which was held virtually during January 17-19, 2021. The conference was planned to take place in Copenhagen, Denmark, but changed to an online event due to the COVID-19 pandemic. The 23 papers presented in this volume were carefully reviewed from 48 submissions. VMCAI provides a forum for researchers working on verification, model checking, and abstract interpretation and facilitates interaction, cross-fertilization, and advancement of hybrid methods that combine these and related areas. The papers presented in this volume were organized in the following topical sections: hyperproperties and infinite-state systems; concurrent and distributed systems; checking; synthesis and repair; applications; and decision procedures.