Cory's DC Y2K Weather Report #109 is Online...

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Here it is, folks...

Cory Hamasaki's DC Y2K Weather Report #109

-- Nabi Davidson (nabi7@yahoo.com), January 29, 1999

Answers

Nabi, How come you are always the first to know? b

-- bb (b@b.b), January 29, 1999.

From Cory's latest:

For programmers, the most powerful technology I have found is Automata Theory. This stuff is like nuclear power. GREP, generalized regular expression parser, you can't even understand the name unless you understand Automata and Language Theory. The clueless think GREP is like grab. To understand Automata, you have to know Eulerian circuits and set theory. Lots of stuff to learn

I admire Cory's spirit of educational enthusiasm, but statements like this give me pause. I thought Cory was such a total uber-geek and everything. Regular expresions are certainly no big deal from the user's point of view. They are provided for pattern matching on text strings in the extremely convenient Perl scripting language, and are provided as a tool for ordinary end-users in the high-end Macintosh word processing system, NisusWriter 5.04 , from Nisus.

As for the underlying implementation and theory, sure it can get a little complicated depending on the degree of flexibility the implementation allows (Perl's is quite powerful), and the theoretical base in regular algebras could be abstruse if you want to get into really deep theory, but the basic concept is not much more than the common mechanism of finite-state automata (FSA), the formal properties of which were pretty well defined and exhausted by Noam Chomsky in the 1950's. And he isn't even a programmer (or a mathematician). Someone like Cory with an MS in computer science should have covered regular algebras and FSA's in his first semester.

A completely readable and straight-forward explanation of using RE's is to be found in the book:

Mastering Regular Expressions : Powerful Techniques for Perl and Other Tools (Nutshell Handbook) by Jeffrey E. Friedl

Or just read the extremely entertaining and lucid writing of Larry Wall in the chapter on regular expression in his magnum opus Programming Perl

-RCat

-- Runway Cat (Runway_Cat@hotmail.com), January 29, 1999.


Sorry, I wasn't clear. I was alluding to the use of FSA as a systems design tool and not the use of a text scanning command implementing RE.

I believe that Language and Automata Theory are powerful tools for designing clean, sparse, and correct systems.

I do not believe that Formal Methods can be used to prove the correctness of real world systems due to the complexity of such systems.

-- I'm clueless (cory@you.know.where), January 29, 1999.


Yes, there is no known general method for formal correctness proof of software that applies to anything much bigger than a 15-line bubble sort.

Cory, did you take Doug Maurer's graduate cs course in software correctness and verification when you were at GWU ? Holy ***t ! And that guy is world expert in the field.

-RCat

-- Runway Cat (Runway_Cat@hotmail.com), January 29, 1999.


Cat, I had no idea you knew this kind of theoretical mathematical stuff..I always had the impression you were a military sort of person..

What ELSE do you know that we should be aware of? ;)

-- Leo (lchampion@ozemail.com.au), January 29, 1999.



Leo, my guiding principle in life is summarized by WW's "check six". I always try to learn anything that could end up being relevant, as thoroughly as possible. Only the paranoid survive ! Along the way you pick up jobs, degrees, patents, and other external junk, as byproducts.

-RCat

-- Runway Cat (runway_cat@hotmail.com), January 29, 1999.


I'm psychic, b; I think it comes from eating lemon grass chicken at the Queen Bee:-)...

-- Nabi Davidson (nabi7@yahoo.com), January 29, 1999.

Automata theory is taught to sophomore undergraduate computer science majors. Hardly uber-geek material; it's thin vanity at best.

-- Declan McCullagh (declan@well.com), January 29, 1999.

go beat your wife you worthless twirp.

-- bs (declan@sucks.crap), January 30, 1999.

Runway Cat, you astound me ! Now explain something much simpler like"check six".Is it like lock and load?

-- Sue (deco100@aol.com), January 31, 1999.


Sue ,

Imagine the face of a clock ,with 12 0'clock being to your front.

Check six means to check your rear position . In military jargon .

Sorry Runway Cat :o)

-- Mike (mickle2@aol.com), January 31, 1999.


Runaway Cat,

sadly no, but I did have the good luck to have an exceptional professor. We used three texts but most of the material came from Ullman, Hopcroft "Introduction to Automata Theory, Languages, and Computation."

I'm not sure what Declan is referring to. The preface to Ullman states, "Both authors have used Chapters 1 though 8 for a senior-level course, omitting only the material on inherent ambiguity in Chapter 4 and portions of Chapter 8." Ullman teaches at Princeton and Hopcroft, Cornell.

Their book has 14 chapters and frankly, I was pretty lost although I wrote down every word the professor spoke, even a coughing fit, transcribed), but being lost and clueless, that's my normal state, call it S0.

-- cory (cory@you.know.where), January 31, 1999.


Re : Check six - in the hospital we call it CYA, cover your a**.

-- Tricia the Canuck (jayles@telusplnanet.net), February 01, 1999.

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