"The authors of this book are well-known specialists in the area of homological classification of monoids. The presentation is extremely clear and incisive. Without a doubt, the book could serve as a textbook for a very good graduate course on representation theory of monoids, homological algebra and category theory." Mathematical Reviews
"The material of the book is well organised and suitable for a broad audience interested in monoids, acts, non-abelian categories as well as in formal languages, automata theory and other applications of semigroups. The book is comprehensive and self-contained and can be used both as study material for courses on representation theory on monoids, homological algebra and category theory, and as a handbook for students and researchers in the area. This is why the book should not be missing in any library of the faculty of mathematics of any university." Zentralblatt für Mathematik
"The material of the book is well organised and suitable for a broad audience interested in monoids, acts, non-abelian categories as well as in formal languages, automata theory and other applications of semigroups. The book is comprehensive and self-contained and can be used both as study material for courses on representation theory on monoids, homological algebra and category theory, and as a handbook for students and researchers in the area. This is why the book should not be missing in any library of the faculty of mathematics of any university." Zentralblatt für Mathematik