The structure of regular semigroups is studied in full generality. The principal tool used in this is the concept of a (regular) biordered set which abstractly characterizes the set of idempotents of a regular semigroup. The category of inductive groupoids is then defined as the category whose objects are pairs consisting of an ordered groupoid and an order-preserving functor of the chain groupoid of a biordered set whose vertex map is a bijection, and whose morphisms are certain commutative diagrams in the category of ordered groupoids. It is shown by an explicit construction that every regular semigroup can be constructed from an inductive groupoid and that the category of inductive groupoids is equivalent to the category of all regular semigroups. This construction is then applied to obtain the structure of all fundamental regular semigroups and all idempotent generated regular semigroups. The paper ends with a study of biordered sets of some important classes of regular semigroups.

This work offers concise coverage of the structure theory of semigroups. It examines constructions and descriptions of semigroups and emphasizes finite, commutative, regular and inverse semigroups. Many structure theorems on regular and commutative semigroups are introduced.;College or university bookstores may order five or more copies at a special student price which is available upon request from Marcel Dekker, Inc.

The conference was a rare occasion for different schools and perspectives to meet in a single event, bringing together researchers interested in semigroups, automata and languages. The proceedings contain both surveys and research reports, which have been carefully refereed. They should be of value to both mathematicians and computer scientists.

Semigroups is a collection of papers dealing with models of classical statistics, sequential computing machine, inverse semi-groups. One paper explains the structure of inverse semigroups that leads to P-semigroups or E-unitary inverse semigroups by utilizing the P-theorem of W.D. Nunn. Other papers explain the characterization of divisibility in the category of sets in terms of images and relations, as well as the universal aspects of completely simple semigroups, including amalgamation, the lattice of varieties, and the Hopf property. Another paper explains finite semigroups which are extensions of congruence-free semigroups, where their set of congruences forms a chain. The paper then shows how to construct such semigroups. A finite semigroup (which is decomposable into a direct product of cyclic semigroups which are not groups) is actually uniquely decomposable. One paper points out when a finite semigroup has such a decomposition, and how its non-group cyclic direct factors, if any, can be found. The collection can prove useful for mathematicians, statisticians, students, and professors of higher mathematics or computer science.

This book is a collection of selected papers presented at the International Conference on Semigroups and Applications, held at the Cochin University of Science and Technology, India, from December 9–12, 2019. This book discusses the recent developments in semigroups theory, category theory and the applications of these in various areas of research, including structure theory of semigroups, lattices, rings and partial algebras. This book presents chapters on ordering orders and quotient rings, block groups and Hall’s relations, quotients of the Booleanization of inverse semigroup, Markov chains through semigroup graph expansions, polycyclic inverse monoids and Thompson group, balanced category and bundle category. This book will be of much value to researchers working in areas of semigroup and operator theory.