Martin Davis & Ron Sigal 
Computability, Complexity, and Languages [EPUB ebook] 
Fundamentals of Theoretical Computer Science

Computability, Complexity, and Languages is an introductory text that covers the key areas of computer science, including recursive function theory, formal languages, and automata. It assumes a minimal background in formal mathematics. The book is divided into five parts: Computability, Grammars and Automata, Logic, Complexity, and Unsolvability. — Computability theory is introduced in a manner that makes maximum use of previous programming experience, including a "universal" program that takes up less than a page. — The number of exercises included has more than tripled. — Automata theory, computational logic, and complexity theory are presented in a flexible manner, and can be covered in a variety of different arrangements.