The aim of the Expositions is to present new and important developments in pure and applied mathematics. Well established in the community over more than two decades, the series offers a large library of mathematical works, including several important classics. The volumes supply thorough and detailed expositions of the methods and ideas essential to the topics in question. In addition, they convey their relationships to other parts of mathematics. The series is addressed to advanced readers interested in a thorough study of the subject. Editorial Board Lev Birbrair, Universidade Federal do Ceará, Fortaleza, Brasil Walter D. Neumann, Columbia University, New York, USA Markus J. Pflaum, University of Colorado, Boulder, USA Dierk Schleicher, Jacobs University, Bremen, Germany Katrin Wendland, University of Freiburg, Germany Honorary Editor Victor P. Maslov, Russian Academy of Sciences, Moscow, Russia Titles in planning include Yuri A. Bahturin, Identical Relations in Lie Algebras (2019) Yakov G. Berkovich, Lev G. Kazarin, and Emmanuel M. Zhmud', Characters of Finite Groups, Volume 2 (2019) Jorge Herbert Soares de Lira, Variational Problems for Hypersurfaces in Riemannian Manifolds (2019) Volker Mayer, Mariusz Urbański, and Anna Zdunik, Random and Conformal Dynamical Systems (2021) Ioannis Diamantis, Boštjan Gabrovšek, Sofia Lambropoulou, and Maciej Mroczkowski, Knot Theory of Lens Spaces (2021)

The series is aimed specifically at publishing peer reviewed reviews and contributions presented at workshops and conferences. Each volume is associated with a particular conference, symposium or workshop. These events cover various topics within pure and applied mathematics and provide up-to-date coverage of new developments, methods and applications.

Contents: B.P. Alimpic, D.N. Krgovic: Some Congruences on Regular Semigroups.- J. Almeida: On Pseudovarieties of Monoids.- K. Culik II, J. Karhumäki: Systems of Equations over a Finitely Generated Free Monoid Having an Effectively Findable Equivalent Finite Subsystem.- M. Demlová, V. Koubek: Minimal Congruences and Coextensions in Semigroups.- V. Fleischer, U. Knauer: Endomorphisms Monoids of Acts are Wreath Products of Monoids With Small Categories.- J. Fountain: Free Right H-Adequate Semigroups.- G.A. Freiman, B.M. Schein: Group and Semigroup Theoretic Considerations Inspired by Inverse Problems of the Additive Number Theory.- S.M. Goberstein: Correspondences of Semigroups.- P. Goralcik, V. Koubek: On Universality of Extensions.- U. Hebisch, L.C.A. van Leeuwen: On Additively and Multiplicatively Idempotent Semirings and Partial Orders.- P.R. Jones: Congruence Semimodular Varieties of Semigroups.- M. Katsura, H.J. Shyr: Decomposition of Languages into Disjunctive Outfix Codes.- G. Lallement: Some Algorithms for Semigroups and Monoids Presented by a Single Relation.- W. Lex: Remarks on Acts and the Lattice of Their Torsion Theories.- D.Lippert, W. Thomas: Relativized Star-Free Expresssions, First-order Logic, and a Concatenation Game.- E.S. Ljapin: Semigroup Extensions of Partial Groupoids.- K. Madlener, F. Otto: On Groups Having Finite Monadic Church-Rosser Presentations.- R.B. McFadden: Automated Theorem Proving Applied to the Theory of Semigroups.- A. Nagy: Subdirectly Irreducible WE-2 Semigroups with Globally Idempotent Core.- J. Okninski: Commutative Monoid Rings with Krull Dimension.- M. Petrich, G. Thierrin: Languages Induced by Certain Homomorphisms of a Free Monoid.- G. Pollák: Infima in the Power Set of Free Semigroups.- N.R. Reilly: Update on the Problems in 'Inverse Semigroups' by M. Petrich.- K.D. Schmidt: Minimal Clans: a Class of Ordered Partial Semigroups Including Boolean Rings and Lattice-ordered Groups.- J.-C. Spehner: Les systèmes entiers d'équations sur un alphabet de 3 variables.- M.B. Szendrei: A New Interpretation of Free Orthodox and Generalized Inverse *-semigroups.- P.G. Trotter: Varieties of Completely Regular Semigroups: Their Injectives.- H.J. Weinert: Generalized Semialgebras Over Semirings.