Regular expressions, Equivalence of regular expression and FSA, Equivalence of type 3 grammars and FSA, Pumping lemma , Closure and decidability results , Myhill- Nerode theorem, Minimization, FSA with output, Problems - Pushdown Automata, Acceptance by final state and empty store, Equivalence to CFG , Deterministic PDA - Problems and Solutions - Turing Machines - Construction, Techniques of TM construction , TM as acceptor and i/o device , Problems . Generalized and restricted versions - Halting problems - Universal TM-recursive and recursively enumerable sets - Decidability - Rices Theorem , PCP - Time and Tape complexity of TM , P and NP, Cooks theorem - NP-Complete Problems - Advanced topics , Regulated rewritin , L systems Grammar system - New Paradigms of computing , DNA computing , Membrane computing