This Festschrift is published in honor of Yuri Gurevich’s 80th birthday. An associated conference, YuriFest 2020, was planned for May 18–20 in Fontainebleau, France, in combination with the 39th Journées sur les Arithmétiques Faibles also celebrating Yuri’s 80th birthday. Because of the coronavirus situation, the conference had to be postponed, but this Festschrift is being published as originally planned. It addresses a very wide variety of topics, but by no means all of the fields of logic and computation in which Yuri has made important progress.

This Festschrift is published in honor of Yuri Gurevich's 75th birthday. Yuri Gurevich has made fundamental contributions on the broad spectrum of logic and computer science, including decision procedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. Many of these areas are reflected in the 20 articles in this Festschrift and in the presentations at the "Yurifest" symposium, which was held in Berlin, Germany, on September 11 and 12, 2015. The Yurifest symposium was co-located with the 24th EACSL Annual Conference on Computer Science Logic (CSL 2015).

This Festschrift is published in honor of Yuri Gurevich''s 75th birthday. Yuri Gurevich has made fundamental contributions on the broad spectrum of logic and computer science, including decision procedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. Many of these areas are reflected in the 20 articles in this Festschrift and in the presentations at the "Yurifest" symposium, which was held in Berlin, Germany, on September 11 and 12, 2015. The Yurifest symposium was co-located with the 24th EACSL Annual Conference on Computer Science Logic (CSL 2015).

Yuri Gurevich has played a major role in the discovery and development of - plications of mathematical logic to theoretical and practical computer science. His interests have spanned a broad spectrum of subjects, including decision p- cedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. In May 2010, Yuri celebrated his 70th birthday. To mark that occasion, on August 22, 2010,a symposium was held in Brno, the Czech Republic, as a sat- lite event of the 35th International Symposium on Mathematical Foundations of Computer Science (MFCS 2010) and of the 19th EACSL Annual Conference on Computer Science Logic (CSL 2010). The meeting received generous support from Microsoft Research. In preparation for this 70th birthday event, we asked Yuri’s colleagues (whether or not they were able to attend the symposium) to contribute to a volume in his honor. This book is the result of that e?ort. The collection of articles herein begins with an academic biography, an annotated list of Yuri’s publications and reports, and a personaltribute by Jan Van den Bussche. These are followed by 28 technical contributions. These articles – though they cover a broad range of topics – represent only a fraction of Yuri’s multiple areas of interest. Each contribution was reviewed by one or two readers. In this regard, the editors wish to thank several anonymous individuals for their assistance.

This Festschrift is published in honor of Yuri Gurevich’s 80th birthday. An associated conference, YuriFest 2020, was planned for May 18–20 in Fontainebleau, France, in combination with the 39th Journées sur les Arithmétiques Faibles also celebrating Yuri’s 80th birthday. Because of the coronavirus situation, the conference had to be postponed, but this Festschrift is being published as originally planned. It addresses a very wide variety of topics, but by no means all of the fields of logic and computation in which Yuri has made important progress.

This Festschrift is published in honor of Yuri Gurevich's 75th birthday. Yuri Gurevich has made fundamental contributions on the broad spectrum of logic and computer science, including decision procedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. Many of these areas are reflected in the 20 articles in this Festschrift and in the presentations at the "Yurifest" symposium, which was held in Berlin, Germany, on September 11 and 12, 2015. The Yurifest symposium was co-located with the 24th EACSL Annual Conference on Computer Science Logic (CSL 2015).

This Festschrift is published in honor of Yuri Gurevich''s 75th birthday. Yuri Gurevich has made fundamental contributions on the broad spectrum of logic and computer science, including decision procedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. Many of these areas are reflected in the 20 articles in this Festschrift and in the presentations at the "Yurifest" symposium, which was held in Berlin, Germany, on September 11 and 12, 2015. The Yurifest symposium was co-located with the 24th EACSL Annual Conference on Computer Science Logic (CSL 2015).

Yuri Gurevich has played a major role in the discovery and development of - plications of mathematical logic to theoretical and practical computer science. His interests have spanned a broad spectrum of subjects, including decision p- cedures, the monadic theory of order, abstract state machines, formal methods, foundations of computer science, security, and much more. In May 2010, Yuri celebrated his 70th birthday. To mark that occasion, on August 22, 2010,a symposium was held in Brno, the Czech Republic, as a sat- lite event of the 35th International Symposium on Mathematical Foundations of Computer Science (MFCS 2010) and of the 19th EACSL Annual Conference on Computer Science Logic (CSL 2010). The meeting received generous support from Microsoft Research. In preparation for this 70th birthday event, we asked Yuri’s colleagues (whether or not they were able to attend the symposium) to contribute to a volume in his honor. This book is the result of that e?ort. The collection of articles herein begins with an academic biography, an annotated list of Yuri’s publications and reports, and a personaltribute by Jan Van den Bussche. These are followed by 28 technical contributions. These articles – though they cover a broad range of topics – represent only a fraction of Yuri’s multiple areas of interest. Each contribution was reviewed by one or two readers. In this regard, the editors wish to thank several anonymous individuals for their assistance.