Theory of semigroups and Applications. Kalyan B. Sinha, Sachi Srivastava. Texts and Readings in Mathematics. Volume 74 (2017).
Semigroups (or groups, in many situations) of maps or operators in a linear space have played important roles, mathematically encapsulating the idea of homogeneous evolution of many observed systems, physical or otherwise. As an abstract mathematical discipline, the theory of semigroups is fairly old, with the classical text, Functional Analysis and Semigroups by Hille and Phillips being probably the first one of its kind. Indeed, there have been a good number of books and monographs on this topic written over the years, many of which have been referred to in the present text.