Introduction to Automata Theory, Languages, and Computation (2nd Edition) (Hardcover)

Hopcroft & Ullman wrote the classic text way back in 1969, and then
revised it in 1979. It was pretty much the standard text the world
over for an introduction to the theory of computation.

But over the last two decades, more and more people have been studying
Computer science, and many of them have no time for theory and
formalism and all the 'dry stuff' ..........

The authors point out that because of such reasons and also because
nowadays there's little research in the theory of computation per se,
and more in its applications, they've written a book to cater to today's
students.

Which, in other words, means they've simplified the presentation, tried
to provide intuition whenever possible, given lots more examples and
done away with some of the more difficult material.

This approach puts the book into direct competition with Michael Sipser's
excellent 'Introduction to the theory of computation', a contest it
cannot win, though it might be a respectable second.

Almost all topics are motivated by giving examples of how they're
related to applications in the 'real world', and similar to
Sipser's 'proof idea' approach, the authors first present a topic
informally and then formally, thus gently leading the reader to
the formal proofs.

This book sets out to do pretty much the same as what Sipser's book
does, ie to provide a readable, user-friendly introduction to the
theory of computation with lots of examples and intuitive approach
to problems wherever possible, but Sipser's already done an
'optimal' job.

Moreover, this book tries to be 'chatty', which i'm afraid is just
not the authors' style - the 'economy of expression', which has long
which has long been the hallmark of the legendary textbooks by
Aho,Hopcroft and Ullman, is sadly missing here.

Which means that this may not be the book for you if you're pressed
for time - but on the other hand, if you want to led gently to the
proofs and results with lots of examples and motivation, then this
might be just the book for you.

So all in all, it definitely worth a read - in fact, i'd say
it's still among the top textbooks around.

In fact, i would suggest that you read both this and Sipser, if you
have the time. Otherwise Sipser's the better choice for most of the
part, though it may not cover all the topics you need.

And if you're comfortable with a terse, concise & rigorous
presentation, then the earlier edition of this book is still
unbeatable - and you'll surely need it if you want to pursue research
in this area.

It's very simple: Don't use it if _____, and do use it if ____.

Do NOT even THINK of buying this book:

1. If this is going to be your first brush with formal languages and the theory of computation.

2. If you need to get motivated to learn the subject, and you need that "first grasp" on it.

3. If you're taking a first course in the subject, and if you have an IQ below 130!

On the other hand,

You MUST buy this book:

1. If you already have some background, and you want a larger picture.

2. If you will often need an authoritative source for proofs etc.

3. If you need a reference for formalizing concepts touched on elsewhere.

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.