Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Re: Introduction to Automata Theory, Languages and Computation

by Dominus (Parson)
on Oct 10, 2001 at 23:53 UTC ( [id://118096]=note: print w/replies, xml ) Need Help??


in reply to Introduction to Automata Theory, Languages and Computation

Can you talk about how this new edition differs from the old edition?

I have a copy of the first edition of this book, and I've always thought it was one of the worst computer science texts I'd ever read. I found it turgid and confusing. The arguments are all overformalized, with excessive notation that obscures what's really going on. You say that the formal proofs are preceded by informal sketches, and I hope that's true, because they sure didn't do it in the first edition. For example, I know from experience that many people are deeply confused by the first edition's explanation of the pumping lemma for regular languages. But I also know that there's nothing hard about the pumping lemma, because I've been able to teach high school students about it in half an hour. This isn't a boast, because I think anyone could do the same. But the first edition of this book didn't do it.

The first edition's treatment of NP-completeness is similarly turgid. They use nonstandard terminology and nonstandard definitions (which I hope they cleaned up for the new edition), but that isn't my real complaint. My real complaint is that even I already know all about everything they're going to say about NP-completeness, I can't understand their discussion. It's just too convoluted. (I'd invite interested readers to compare the treatment in the Hopcroft and Ullman book with the treatment in Garey and Johnson. I did this and found it educational as an example of how to write a good technical paper.)

You also said that "The style of the book is vey application-oriented." That would be a welcome change from the first edition, but I wish you had given an example, because I'm skeptical. On page 57 of the first edition is a section titled "Applications of the pumping lemma." The section contains a detailed secription of how to construct a pumping lemma proof that a language is not regular. What language? No language in particular. The title notwithstanding, the promised application is nowhere to be found. Earlier, on page 46, there is a paragraph about the use of regular expressions in the unix text editor. It's really too little. More than once I've been asked by CS students what this finite automaton nonsense was good for, and they were shocked when I said "Oh, that's how 'grep' works." The book doesn't tell you and it doesn't get close to communicating any of the important uses of regular expressions. It looks like section 3.3 of the new edition may remedy this, but I can't tell.

Anyway, I'm glad you liked the new edition, and if what you say is true, I guess the authors have learned something since 1979, when the first edition appeared. The book's web page does say that it "features more explanations and intuition, more applications, and a selection of topics with an eye toward balancing the need for relevance with the need to master the foundations of computer science." So I suppose from this that I'm not the only person who had big complaints about the first edition. But I wish you had been able to compare the new edition with the first edition, and I'd be reluctant to buy the new version without taking a very close look over some of the material to make sure it really had been improved.

--
Mark Dominus
Perl Paraphernalia

Replies are listed 'Best First'.
Re: Re: Introduction to Automata Theory, Languages and Computation
by clemburg (Curate) on Oct 11, 2001 at 12:18 UTC

    Can you talk about how this new edition differs from the old edition?

    Sure, no problem. I don't own the old edition, but I have heard enough bad comments that I feel I can comment on the new one.

    I have a copy of the first edition of this book, and I've always thought it was one of the worst computer science texts I'd ever read.

    This has profoundly changed, I'd say. The new book comes nowhere close to being "one of the worst". The topic of the book will not appeal to all people, but the coverage of the material is clear and easy to understand. Please note again that I have no formal background in mathematics (I originally have studied psychology and brain research, and statistics is pretty much the only part of higher math I feel somehow educated about). Despite this, I was able to cover a lot of ground in short time, due to the excellent introductory sections in the book.

    I found it turgid and confusing. The arguments are all overformalized, with excessive notation that obscures what's really going on.

    That has definitively changed. The authors also note in the introduction that they did change this for a number of reasons:

    • back when the first edition was published, automata theory was still in the active research area; today it is "a staple of the undergraduate curriculum" as they put it
    • the old book was intended for graduate students, while the new book is intended for use in the undergraduate curriculum
    • since computer science has grown so large, automata theory can today occupy only a limited space in a curriculum
    • "Fourthly, CS has become a more vocational subject, and there is a severe pragmatism among many of its students."

    You say that the formal proofs are preceded by informal sketches, and I hope that's true, because they sure didn't do it in the first edition.

    Oh yes, it's true. Just take a look at the book in your nearest library.

    For example, I know from experience that many people are deeply confused by the first edition's explanation of the pumping lemma for regular languages. But I also know that there's nothing hard about the pumping lemma, because I've been able to teach high school students about it in half an hour. This isn't a boast, because I think anyone could do the same. But the first edition of this book didn't do it.

    The pumping lemma took me about half an hour to cover, mostly because there is a missing assumption in the proof (the language must have no bound on the length of its members, meaning it is infinite, for the pumping lemma to work). I found the explanation in the book very clear and easy.

    The first edition's treatment of NP-completeness is similarly turgid.

    Sorry, I can't really comment on this, since I have not yet covered this part of the book. I am still with Turing machines and undecidability. Maybe next week :-) ...

    You also said that "The style of the book is vey application-oriented." That would be a welcome change from the first edition, but I wish you had given an example, because I'm skeptical.

    Take a look at sections 2.1 (using a finite automaton to validate a simple e-commerce protocol), 3.3 and 3.4 (UNIX Regexes and Algebraic Laws for Regular Expressions) and 5.3 (YACC and XML as applications of context free grammars). That pretty much explains what I mean. OK, maybe I should have said "The book is written with an eye towards possible applications of the theoretical material covered." and not "very application oriented". The latter may convey a wrong message.

    Anyway, I'm glad you liked the new edition, and if what you say is true, I guess the authors have learned something since 1979, when the first edition appeared.

    Indeed I think they have.

    But I wish you had been able to compare the new edition with the first edition, and I'd be reluctant to buy the new version without taking a very close look over some of the material to make sure it really had been improved.

    I'd do so, too, if I were you. It is hard to believe a book can change so much. OTOH, I *really* like this text. It opened up the world of a big part of "classic" formal computer science for me. That is no little thing. Maybe I am just too excited about the book, but I still think it is definitively worth a look on the next trip to the library or bookstore.

    Christian Lemburg
    Brainbench MVP for Perl
    http://www.brainbench.com

      Thanks a lot for elaborating on the changes between the first and second editions. Your cites from the introduction are especially helpful to me.

      I will certainly take a look at the new edition.

      --
      Mark Dominus
      Perl Paraphernalia

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://118096]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (8)
As of 2024-03-28 11:29 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found