An Introduction to Automata Theory, Languages, and Computation

I've just passed my exam on Theory of Computation, and I've used both editions of this text. Frankly speaking, I couldn't choose one of the two should I keep only one of them.Whereas the first was full of strict formalism, the second has traded this for a more discursive approach. Whereas the first reported theorems name (of their authors), the second has traded this for a richer bibliography at the end of the chapters. And more objectively, the first edition covered more "classical" topics with shorter treatments than the second, but this last treats survived topics with richer details (starting from the first chapter on mathematical basis for the course) and with updated examples of applications (XML and Markup Languages, e-commerce for DFA, etc).This said, you know why I can't decide. A discursive approach is of course always desiderable, especially if you're completely new to a subject, but a strong notation is helpful in my mind because it improves communication and removes ambiguities. Hence, the best approach would probably have been a mix of the two, or halfway the two.As a second matter, having a rich bibliography is surely helpful both for further studies and as a reference, but it's quite tedious to look at the index and be unable to find something like "Kleene theorem": you've to dive into bibligraphy to discover that "L is an L(DFA) if and only if it also is L(REG)" is something that has been studied by Kleene.Finally, I surely can't question the removal of the complexity theory part since it is in the right of the authors to remove "optional topics" (if you use the book for a course on Theory of Computation only) and give a more focused target to the book, but removing stuff like the Myhill-Nerode theorem make things annoying since virtually every course on Automata theory and Computation includes it (like my one did, as well as the course on Languages and Compilers), so you have to look for it elsewhere if your only one book is this second edition.I would give four stars, should I keep in heavy account the radical changes they made over the first edition and that includes the removal of some stuff, important on my opinion. But ... this is just my opinion, and since it is a very well written and informative book (rich of many details that other texts lack of) and surely one of the bests in the area (I've had 4-5 books in my hands for this course), that's why I gave it 5 stars.

This is the one book that I refer to time and time again for all of my automata-theory needs. It covers all the fundamental theorems of finite-state automata such as determinization and the pumping lemma in a clear, concise manner. Excellent coverage of context-free grammars, with excursions into generative power, normalization and parsing. The book is rigorously mathematical, yet easy to understand.I came to this book fifteen years ago as a grad student after reading Lewis and Papadimitriou (which is good, but overly detailed on notation where context would suffice), used it as a professor teaching automata theory at Carnegie Mellon, and now use it as a software engineer for a speech recognition company that builds grammars.

I needed a book which would speed me up with my GRE computer science subject test (part III: Theory). Having non US and non english language based Bachelor Degrees in CS and Math, I needed something to both learn the more precise terminology and at the same time to gather my prevous knoweldge of the subject. After little bit of browsing and examining of reviews, book contents and browsing pages in bookstores, I decided to buy this one. I admit that I had a solid knowledge of almost all chapters of the book and that the book might be hard to swallow for someone who is not a little bit familiar in mathematical logic and elementary math but otherwise, the book is excellent. Even authors admit that previous editions were more demanding and in this one they introduced many easier examples and appropriate pictures and diagrams so I really did not have any problems understanding every concept. After each chapter exercises are given and while they are useful, I would prefer solutions embedded into the book (as in Knuth's Art of Programming). Rather that doing that, authors put solutions (to selected exercises) on their web page which is not bad but the book would be more complete (and probably more expensive) with solutions inside. I would pay $20 more for that version though... I also must say that I really appreciate hard cover and excellent quality paper (these unfortunately raised the price) Overall, this is an excellent book and if you are in a similar situation as me, I would recommend this one.

A predecessor of the book was published in 1969 titled "Formal Languages and Their Relation to Automata." It was re-written in 1979. This is a classical textbook for last year undergraduate students or postgraduate students in computer science, especially those who are going to deal with computer languages, artificial intellegence, compiler design, computational complexity and so on. One of the author, J. E. Hopcroft, is the Turing Award winner of 1987.I have both versions of the book and I'd like recommend every computer science student spend some time on reading it.