Graph Theory

15+ years ago as an undergraduate I was interested in graphs. Manos then suggested that I should read Christos‘ PhD thesis. Then came work. Then came this paper. Then came even more work. I forgot about graphs. My interest was renewed after spending family vacations with a theorist’s family. Aris presented me with a challenge, while this fall, this man taught me the foundations from a non-CS perspective.

In the words of Steve Yegge:

“Graphs are, like, really really important. More than you think. Even if you already think they’re important, it’s probably more than you think.”

Notice the “really really important” part. For it is not “really2 important”; rather it is more of “reallyn important” (for n >> 2). Go down to your library and read Bela Bollobas’ “Modern Graph Theory” (I found its predecessor “Graph Theory – An Introductory Course”) or even Reinhard Diestel’s “Graph Theory” which is also available online*. For those who read Greek, here is a quick introduction (definitions and theorems but no proofs): Εφαρμογές Θεωρίας Γραφημάτων.

In an era when (almost) everyone seems to be talking about the social graph, or applications that make use of it, you need the mathematical background. If you have an idea that builds on social networks it is almost inevitable that its development and implementation will make use of theorems or more general results of graph theory. So, since you will have to deal with it, why not be prepared? Or even if you have devised a graph data model that can kill the RDBMS+, why not use the theory to support the argument?


[*] – Originally I wanted to write a simple “post-it” on Diestel’s book. However, in the process I decided to make it a typical blog post of three to four paragraphs. You may even want to dig more by reading Bernie Hogan’s “Using Information Networks to Study Social Behavior: An Appraisal “, the stuff over at the NetWiki and the articles in the graph theory section of MarkCC’s Good Math, Bad Math.

[+] – Hank, this is not a polemic on your view on RDBMS; we have already agreed on what parts of this view we disagree.

Why I like running MIMEDefang

I had a talk with a friend the other day and he told me that he does not run MIMEDefang on his systems. Well I do and since most people run MIMEDefang just to be able to run ClamAV and SpamAssassin from one place, I want to explain why. Because when you have a hammer it is better to have more than two nails.

I like running MIMEDefang because it gives me a Perl interpreter at hand and a set of handy routines to manipulate every message that passes through the mail server (header and body). So for any weird idea that I have and I need a proof of concept, I have a full programming language on my email server waiting to run it. And if I have performance issues, well I can always (re)write it in C.

I really think it pays off to invest sometime to learn how to change stuff in mimedefang-filter(5) and how to write your own versions of the filter_* routines.

face-off

Για να δούμε τι θέλει να μάθει η foteinoula:

  • Όνομα: Γιώργος
  • Γεννέθλια: 4 Μαρτίου
  • Ζώδιο: Ιχθείς;
  • Χρώμα ματιών: Καφέ;
  • Χρώμα μαλλιών: Καφέ με άσπρες τρίχες;
  • Έχεις ερωτευθεί ποτέ; ΝΑΙ
  • Μουσική που ακούς: Jazz και ότι καλό έβγαλε η Death Row μέχρι το 1997
  • Χαρακτήρας Disney: Ο Ήτα-Βήτα, ο Φάντομ Ντακ και ο Γλόμπος
  • Ποιος φίλος / φίλη μένει πιο μακριά; Ο Δημήτρης
  • Πρώτο πράγμα που σκέφτεσαι όταν ξυπνήσεις: Τι ώρα είναι;
  • Κάτι που έχεις πάντα μαζί σου και δεν αποχωρίζεσαι: [it does not compute]
  • Τι έχεις στον τοίχο σου: Μια αφίσα του John Coltrane
  • Τι έχεις κάτω από το κρεβάτι σου: Ξύλινο πάτωμα
  • Αν ήσουν μόνος/η στο σπίτι και άκουγες ένα βάζο να σπάει τί θα έκανες: Θα το μάζευα
  • Αγαπημένος αριθμός: 96
  • Αγαπημένο όνομα: Ειρήνη
  • Χόμπι: Ο Ολυμπιακός
  • Πού θα ήθελες να ήσουν τώρα: Στο κρεβάτι για ύπνο
  • Μία ευχή για το μέλλον: Ανοχή στη βλακεία
  • Αν μπορούσες να ταξιδέψεις στον χρόνο και να γυρίσεις πίσω, σε ποιά εποχή θα πήγαινες: Στο μεσοπόλεμο, για να δω από κοντά το άλμα στην ανάπτυξη της Φυσικής
  • Φωτιά! Πάρε κάτι μαζί σου: Τη γυναίκα μου και τον adamo v2.0
  • Αγαπημένο λουλούδι: Κανένα
  • Αγαπημένη σειρά: Διαστημόπλοιο Αργώ
  • Αγαπημένη ταινία: The Empire Strikes Back
  • Αγαπημένο τραγούδι: Hurricane 2000
  • Αγαπημένο βιβλίο: [it does not compute]
  • Αγαπημένο ρούχο: Κανένα
  • Αγαπημένος καλλιτέχνης: Coltrane
  • Αγαπημένο φαγητό: Σπαγγέτι
  • Με ποιόν χαρακτήρα καρτούν ταυτίζεσαι: Με το κογιότ
  • Κακή συνήθεια: Νεύρα
  • Χαρακτηριστικό της προσωπικότητάς σου που σου αρέσει: [it does not compute]
  • Χαρακτηριστικό της προσωπικότητάς σου που δεν σου αρέσει: Νεύρα
  • Συνηθισμένη ατάκα: Ουστ ρε!
  • Δουλειά που θα ήθελες να κάνεις: Αυτή που κάνω, με καλύτερες συνθήκες όμως
  • Μεγαλύτερος φόβος: Είναι προφανής
  • Πιστεύεις ότι τα κατοικίδια είναι: Χαρά για κάποιους, εφιάλτης για άλλους

The game stops here.

The GBC experience

I just returned from the GBC 2008. Great fun and interesting stuff. Highly reinvigorating when you are in the midst of a lot of things. Some observations:

  • Matt Mullenweg rules!
  • So does Boris Veldhuijzen van Zanten, who by the way gave the most interesting presentation (Boris, Patrick thanks for the beers).
  • After all these years I finally met in person MarkP and GeorgeP. It is a pitty that we did not have much time to catch up. We will catch up next year.

There must be rivers of beer on Ios island…

Tribute to Honor Jim Gray

From DBWorld:

Tribute to Honor Jim Gray
May 31, 2008 @ UC Berkeley

http://www.eecs.berkeley.edu/IPRO/JimGrayTribute

Jim Gray’s family, friends and colleagues have arranged a public day of talks and reminiscences in his honor, to be held on May 31, 2008, at UC Berkeley. All are welcome.

Although Dr. Gray will be officially listed as missing until 2012, his family has asked that we have this Tribute now, to honor him before too much time has passed.

There are two parts to the Tribute. The General Session that begins the day is intended for the general public. The Technical Sessions will go through the afternoon, and are intended for a computer science audience. The organizers request that people wishing to attend the Technical Sessions register in advance on the web, to facilitate planning.

More information, including the program for the day, registration forms, and information on accommodations is available on the web at http://www.eecs.berkeley.edu/IPRO/JimGrayTribute. Questions about event logistics may be directed to jimgraytribute@eecs.berkeley.edu .

The search for Dr. Gray is detailed in Wired Magazine’s article: http://www.wired.com/techbiz/people/magazine/15-08/ff_jimgray

[via DBWorld @ 2007/12/4]

Η Java δεν είναι C…

– Στη Java πατάς την τελεία (.) και σου βγαίνουν οι επιλογές. Δεν είναι σαν τη C που πρέπει να τα γράφεις όλα με το χέρι.

Δεν κατακρίνω αυτόν που το είπε. Αυτοί που τον έμαθαν να σκέφτεται έτσι πρέπει να βρούν τρύπα να κρυφτούν.