The book is meant for a wide range of students doing their undergraduation and postgraduation courses related to Computer Science. All the concepts are elaborated with illustrations. Algorithmic procedures are provided at the necessary locations. Numerous examples are given for similar but different kinds of problems. Problems similar to the examples are given as Exercises. Objective questions with solutions are given at the end of each chapter.The basic concepts of automata theory, various types of automata and their limitations are given with examples. Turing machines are also dealt with in this book and the execution of Turing machines is traced for better understanding. Classification of decidable and undecidable problems is dealt with in detail. The book will also be useful for students who are preparing for competitive examinations.Salient Features Of The Book:Detailed explanation of the concepts in formal languages and automata theory Several pictorial representations for better understanding.Simple stepwise procedure for designing finite and pushdown automata, designing Turing machines for recognizing languages and computing functions.Tracing the execution of the automata and Turing machines designed.Decidability and intractability are dealt with simple illustrations.About 350 solved problems, 200 exercise problems and 225 objective questions with answers.Syllabus covered for Theory of Computation of B.E., B.Tech, BCA, MCA, M.Sc and M.E. of various universities.