James Tauber

by jtauber : Created on Dec. 9, 2006 : Last modified Dec. 9, 2006 : 1 comment (permalink)

Alibi On The Lot

Tom Bennett, my filmmaking partner, is entering to be a contestant on the filmmaking show On The Lot.

His entry includes a trailer for Alibi Phone Network, the short film that Tom wrote and directed and I produced (along with James Marcus), shot, edited and scored.

You can watch his entry (including the trailer) at http://films.thelot.com/films/890. You can also rate it highly if you like ;)

by jtauber : Created on Dec. 9, 2006 : Last modified Dec. 9, 2006 : Categories filmmaking alibi_phone_network : 0 comments (permalink)

XML Beginnings, Part 1

Seeing as it's the 10th Anniversary of XML, I thought I'd reminisce a little about my small involvement in its beginnings.

In 1994, I was interested in two seemingly distinct fields—corpus linguistics and Web publishing—that happened to both have something to do with SGML. So I decided to learn more about SGML.

I rapidly became an SGML snob of sorts, lamenting the state of HTML and arguing on various mailing lists and newsgroups how much better the Web would be with SGML.

Towards the end of 1995, I started to think seriously about some of the things that would be necessary to make SGML on the Web a reality. One component, I thought, would be a way of resolving SGML's formal public identifiers. SGML Open (which became OASIS eventually) had catalogs but they were like hosts files. What was needed was something more like DNS.

So I came up with an extension to SGML Open Catalogs to allow for hierarchical resolution. You can read a version of my proposal at: http://jtauber.com/1996/03/standards/fpi-urn/delegate.html

This got the attention of Eduardo Gutentag at Sun who thought Jon Bosak (who had recently joined Sun from Novell) might be interested. It also got the attention of Paul Grosso who invited me to present the idea to a meeting of SGML Open in early 1996. I was interning at Sun Labs in Chelmsford at the time and Sun agreed to fly me over to Long Beach for the meeting. My idea seemed to be received well—Charles Goldfarb described it as a "dandy" which was very exciting for a 22-year-old SGML aspirant.

I spent some time after the meeting talking to Jon and Eduardo about SGML on the Web.

After my internship, Sun offered me a job (actually a couple of different positions, including running a website for reusable Java classes, but that's another story). I also interviewed with EBT. For personal reasons, however, I decided to move back to Australia.

I was still interested in SGML on the Web, though, and the next component I thought would be necessary was an implementation of the DSSSL stylesheet language. My vision was to build a tool that would output the result of DSSSL to both Tk widgets for online display and something like PDF for printing.

A couple of months after my return to Australia, I was emailing with Jon Bosak about my DSSSL ideas. And that's when he told me some amazing news: he had convinced the W3C to let him set up a group to look at SGML on the Web and he asked if I'd be interested in being part of the group.

(to be continued)

by jtauber : Created on Dec. 5, 2006 : Last modified Dec. 5, 2006 : Categories xml : 0 comments (permalink)

They Can't Hear Us

Pete Lacey has a great post They Can't Hear You on the gap between the corner of the blogosphere I tend to hang around in and what goes on inside most large enterprises:

the typical corporate technologist hasn’t considered REST and decided against it, they haven’t even heard the term. Ditto RelaxNG, Django, Atom, and everything else that makes the Web work and makes working with the Web easy.

Those technologies are each close to my heart, and get talked about by people on my blogroll all the time. Yet, I can confirm, a lot of really smart people in the industry haven't even heard of them. Any of them.

Well worth a read.

by jtauber : Created on Nov. 30, 2006 : Last modified Nov. 30, 2006 : 1 comment (permalink)

PyCon Submission Rejected

Just got the rejection notice for my PyCon submission on pyjamas. The non-positives all had a single criticism: pyjamas isn't mature enough.

I don't quite agree—pyjamas is actually quite far along. Probably didn't help that I conservatively called the last release 0.1 even though it was probably more of a 0.5 :-)

They had a lot more submissions than places, though, so it looks like it will be a great programme, with or without pyjamas.

UPDATE (2006-11-30): The above makes me sound more upset than I am. I know how hard it is to draw a cut line when there are many more submissions than places so I don't envy the job the committee had. I was actually quite pleased that (lack of) maturity was the only negative reason given. That's easy to fix :-) But I'm still wondering if the 0.1 designation counted against me.

by jtauber : Created on Nov. 29, 2006 : Last modified Nov. 30, 2006 : Categories python pycon pyjamas : 5 comments (permalink)

Rosetta Stone

On Sunday, I thought I'd try out the online version of the Rosetta Stone language learning software. It works out much cheaper than buying the CD-ROM.

It uses Macromedia Shockwave which, it turns out, is not available as a Universal Binary yet, only PPC.

So to run the Rosetta Stone language learning software, I have to use Apple's Rosetta.

Funny, I thought. But then to top it all off, HB suggested we go to the British Museum that afternoon. And guess what we saw...

by jtauber : Created on Nov. 29, 2006 : Last modified Nov. 29, 2006 : 1 comment (permalink)

Incompatible SQLite in OS X and Python

I started my porting of Quisition to django last night.

For development, I'm using SQLite as my database, but it seems I've hit a problem with conflicting versions.

Mac OS X comes with SQLite 3.1.3. That's what's used running sqlite3 at the command-line or running django's dbshell.

However, I'm guessing that when my application is running normally, django is using the SQLite that comes with Python 2.5 (which looks like it could be 3.3.5 or something).

As a result, databases created by django cannot be viewed using sqlite3 at the command-line or running dbshell. There must be a file format incompatibility between SQLite 3.1.x and 3.3.x as I get the error message:

Error: unsupported file format

UPDATE: I downloaded SQLite 3.3.8 and built it (although only after working out I needed to do a gcc_select 4.0 first). The new sqlite3 works fine on the django-generated database.

by jtauber : Created on Nov. 25, 2006 : Last modified Nov. 25, 2006 : Categories python django os_x sqlite : 6 comments (permalink)

Non-ACIDic Qantas Upgrades

I just had a bit of fright. I went on Qantas's website to see if I'd been upgraded on either of my flights tomorrow only to discover my reservation for the first flight had been cancelled.

I rang Qantas (whose telephone customer service is always excellent) and they not only assured me I still had a reservation but that I had indeed received an upgrade.

The only theory the representative could offer is that I'd logged into the website at the "split second" (her words) the upgrade was going through and I'd caught it after the economy class reservation had been cancelled but before the business class reservation had gone through. A refresh of the web page confirmed I had indeed between upgraded.

"This sort of thing happens all the time with computers," the helpful representative offered. I guess it does if the system doesn't follow the I in ACID :-)

by jtauber : Created on Nov. 22, 2006 : Last modified Nov. 22, 2006 : 0 comments (permalink)

Pitch Perception Test

As part of his research at Harvard Medical School, Jake Mandell has a nice online pitch perception test that you can do in about 5 minutes.

Jake says that "the test is purposefully made very hard, so excellent musicians rarely score above 80% correct."

I got 80.6% on my first try, but I think Jake is being kind in his quote above because that only places me in the 66th percentile.

UPDATE: Next day I did the test again and got 88.9% (92nd percentile). That's quite a big jump :-)

by jtauber : Created on Nov. 21, 2006 : Last modified Nov. 22, 2006 : Categories music : 7 comments (permalink)

Coordinate Systems and Metrics

In the previous Poincaré Project post about coordinate systems, I introduced two charts that covered the circle and introduced a coordinate system ranging from 0 to 1 on each of them.

At the time I said:

I've arbitrarily ranged the two coordinate systems from 0 to 1 but any continuous parameterisation of the coordinate curve would work.

Here are three examples of different coordinate systems on the blue chart:

The point to show here is that not only is the choice of the end points arbitrary but that the coordinate can change at a different rate depending on where you are. In the second example, the distance between 0.5 and 0.6 is great than that between 0.4 and 0.5 or 0.5 and 0.6.

Notice that we haven't yet introduced any structure to the manifold itself that allows as to talk about distance without (as we've done on this web page) actually identifying the points in our manifold with points in a higher-dimensional euclidian space (in this case the R^2 of the screen).

This notion of the "rate of change" of the coordinate function lets us do so intrinsically, however. Say the distance between the point 0.5 and 0.6 is 5 in some units. Then the ratio of distance to change of coordinate is 5 / (0.6 - 0.5) = 50. Do this again from 0.5 to 0.55, or from 0.5 to 0.51 or from 0.5 to 0.5001. In other words, take the limit to a change in coordinate of 0.

This tells us how much distance is travelled as a proportion of coordinate change at the point 0.5. This "distance travelled as proportion of coordinate change" is called a metric for that coordinate system. Note that it's a function of the point you're at.

If you want to calculate the distance between arbitrary points with coordinates a and b, you take the integral of this metric function between a and b.

This new structure of a manifold with a metric defined on each chart is core not only to the proof of the Poincaré Conjecture but also to Einstein's General Theory of Relativity. In fact, by the time we've covered what we need for Poincaré, we will have covered more than enough mathematics to understand GR too.

One final thought: notice that, in our example, the metric isn't really telling you much about the manifold itself at all. The metric is merely expressing the relationship between the coordinate system and the notion of distance. We'll see shortly, however, that in dimensions higher that one, it goes beyond just telling you something about the coordinate system and allows you to describe the curvature intrinsic to the manifold.

UPDATE: next post

by jtauber : Created on Nov. 19, 2006 : Last modified Nov. 19, 2006 : Categories poincare_project : 0 comments (permalink)

Hans Rosling and Gapminder

I just watched one of the most informative videos I've ever seen: Hans Rosling's Talk at TED.

Not only is it a wonderful example of data visualisation, it is a fascinating, myth-busting look at what's really going on with world health and economic development.

Rosling calls his approach a "fact-based world view". He's also extremely entertaining.

The software behind his visualisations was developed by a non-profit he founded, Gapminder, and is free (as in beer).

Even if you don't check out the software - the video is well worth 20 minutes of your time.

by jtauber : Created on Nov. 18, 2006 : Last modified Nov. 18, 2006 : Categories economics human_development : 0 comments (permalink)

Why A-Sharp is Not B-Flat

I've talked before about note naming but because I was recently IMing with a friend about why A# != Bb I've been thinking about a simpler way to explain it. It also explains why you can have double flats and double sharps (leading to 35 possible note names for 12 different pitches). Here goes...

• the vast majority of western music involves 12 notes in an octave
• the vast majority of western music is based around a scale consisting of 7 of those notes specific to the choice of key (the notes are called the diatonic notes for that key)
• a particular note in a piece is functioning either as a diatonic note or as a note a semitone higher or lower than a diatonic note
• when expressing a note that is functioning as a raised or lowered note, you use the same letter name as the diatonic note you are raising or lowering. e.g. a raised G is G# and a lowered G is Gb.
• if the diatonic note is already written with a sharp, the raised note has a double sharp and the lowered note has a natural symbol
• if the diatonic note is already written with a flat, the raised note has a natural and the lowered note has a double flat
• but in all cases, the letter part of the note name stays the same

So, imagine you're in the key of Gm. The diatonic notes are: G A Bb C D Eb F. What does A# mean? It means you've taken the second note of the scale and raised it. What does Bb mean? It means the third note of the scale.

In 12-tone equal temperament, they may sound the same; you may play them the same on the piano or the guitar. But if the function of the note at a particular point in the piece is as the third note in the Gm scale, you can only write it Bb and not A#. A# means something completely different.

It's the musical equivalent of "hear" versus "here". Just because they are homophonic doesn't mean they are the same word. Similarly, in western tonal music Bb doesn't mean the same as A#.

by jtauber : Created on Nov. 17, 2006 : Last modified Nov. 17, 2006 : Categories music_theory : 20 comments (permalink)

Milton Friedman

Milton Friedman has died at age 94.

While my sympathies are more with the Austrian School than the Chicago School, I found a lot in Friedman I agreed with and certainly a lot I respected. He probably did more than anyone else to educate the more general population about the benefits of free markets over Keynesian-style intervention.

That the use of the word 'liberal' is completely misused in the US is no more clear than in the obituaries I've read that talk about Friedman's opponents being 'liberals'. I can think of few people that better exemplified true liberalism than Friedman himself.

But although I learnt a lot about economics and economic policy from his writings, I think the thing I will always remember most about him is the loving relationship he seemed to have with his wife.

by jtauber : Created on Nov. 16, 2006 : Last modified Nov. 16, 2006 : Categories economics : 0 comments (permalink)

Amazing Filter

When I got my EF 16mm-35mm f/2.8 L lens, I also bought a UV filter for it.

The box has an amazing without filter and with filter example:

Without the filter you couldn't even tell she's wearing a hat! Besides widening the field of view, the filter really brings out her smile. And visible signs of arm folding are dramatically reduced.

All this with one filter. Amazing!

by jtauber : Created on Nov. 16, 2006 : Last modified Nov. 16, 2006 : Categories photography humour : 3 comments (permalink)

Quisition Going Django

I've decided I'm going to port my nascent flashcard site Quisition over to Django. I've started playing around with said web framework and, quite frankly, it's amazing.

Equally amazing is the ongoing Django Book and its comment system.

I've pretty much decided to throw away my home-grown web framework efforts and convert to Django. Hopefully I won't regret it :-)

(Needless to say, I plan to use pyjamas for the client-side parts of Quisition)

by jtauber : Created on Nov. 15, 2006 : Last modified Nov. 15, 2006 : Categories python django quisition : 5 comments (permalink)

System Preferences Accounts Empty

Today I went to System Preferences on Mac OS X and clicked on Accounts.

Nothing happened.

The title bar showed "Loading Accounts..." but never came back with anything.

Clicking on Accounts a second time and the window just went blank.

After rebooting and trying various things, I tried

nidump passwd /

in Terminal, which revealed the "problem". An 'oracle' user had been created (by the Oracle installer) without a realname.

So I did

sudo nicl . -create /users/oracle realname "Oracle"

and it fixed the problem.

Surely Apple could make System Preferences...Accounts a little more robust than this!

by jtauber : Created on Nov. 15, 2006 : Last modified Nov. 15, 2006 : Categories os_x : 0 comments (permalink)

Pyjamas 0.1 Released

I'm delighted to announce the release of pyjamas 0.1.

Pyjamas is a toolkit and library designed to enable writing AJAX applications in Python. It is based on Google's GWT which does the same thing for Java.

The pyjamas home page is at http://pyjamas.pyworks.org/

The goal for 0.1 was to get the GWT examples all mostly working on Firefox.

Thanks to Willie Gollino and Vicente J. Ruiz Jurado for making that possible.

by jtauber : Created on Nov. 6, 2006 : Last modified Nov. 6, 2006 : Categories python ajax pyjamas : 3 comments (permalink)

Scans of Complete Nibble Magazine Available

Nibble was my favourite Apple II magazine in the 1980s.

Recently, I found the official Nibble Magazine site. You can buy a DVD-ROM (or 10 CD-ROMs) with scans of the complete 12.5 years of the magazine.

Needless to say, I've put in my order :-)

by jtauber : Created on Nov. 4, 2006 : Last modified Nov. 4, 2006 : Categories apple_ii : 2 comments (permalink)

PyCon Submission on Pyjamas

I submitted a proposal to PyCon 2007 for a talk on Pyjamas. Playing on the name, I called the talk "Developing Web Applications in Pyjamas". I'll find out in two weeks if it got accepted.

(PS Just occurred to me that "Pycon" is the name of one of the twelve colonies in Battlestar Galactica)

by jtauber : Created on Nov. 1, 2006 : Last modified Nov. 1, 2006 : Categories python pycon pyjamas : 2 comments (permalink)

Reddit Acquisition

Congratulations to the Reddit founders and employees and to Y Combinator on the acquisition!

by jtauber : Created on Oct. 31, 2006 : Last modified Oct. 31, 2006 : 0 comments (permalink)

New Lens

My first Canon L-series lens arrived today. It's the EF 16-35mm f/2.8L USM.

The L-series in Canon lenses is like the M-series in BMW cars. The construction and performance are just at a totally different level than "lesser" models.

You can tell L-series lenses from a distance because they have the "red ring".

I haven't had a chance to try it out yet, but even the external look of it sets it apart: the casing is metal rather than plastic; there is no external change in lens length when focusing or zooming. And as the f/2.8 in the name suggests, there's no change to maximum aperture at different focal lengths.

I'm looking forward to having 16mm. Even though that's 25.6mm equivalent with my APS-C sensor, I can't wait for the extra field of view. And even though f/2.8 isn't quite as open as my 50mm f/1.4, it's by no means shabby and is hopefully worth spending the extra money over the 17-40mm f/4 L.

by jtauber : Created on Oct. 31, 2006 : Last modified Oct. 31, 2006 : Categories photography : 2 comments (permalink)

TRS-80 CoCo and Bedlam

I'm reading Steve Wozniak's autobiography iWoz at the moment and so I've been reminiscing about my early Apple II days. Back in May 2001 when reminiscence last happened in a big way, I spent the weekend writing an Apple II emulator in Python (see ApplePy) :-)

This time, I also started reminiscing about the computer I had before the Apple II, the first generation TRS-80 Color Computer. My strongest memory of the CoCo was using the EDASM ROM cartridge to learn 6809 assembly language programming.

But I also remember playing text adventure games, like Bedlam.

With a bit of Googling, I found a CoCo emulator Java Applet that includes Bedlam. I don't think I ever got the game out as a kid. But last night I completed it in about an hour. Funny how back then it seemed like such a "big" game. In fact, it had only 25 rooms and 5 objects.

Still a lot of fun.

by jtauber : Created on Oct. 29, 2006 : Last modified Oct. 29, 2006 : 1 comment (permalink)

Pyjamas Progress

Good progress has been made recently on pyjamas, the Python port of Google's GWT.

• I've moved the SVN repository to the new pyworks machine: http://svn.pyworks.org/svn/pyjamas/trunk/
• I've installed Trac 0.11dev and have it configured and up and running for pyjamas: http://trac.pyworks.org/pyjamas/
• Willie Gollino has implemented the Dynatable and JSON RPC examples
• Vicente J. Ruiz Jurado has implemented the Desktop App Clone example

A 0.1 release should come shortly now that all the examples have been implemented.

The goal of 0.2 will then be to iron out bugs in those examples and ensure they work on at least Firefox, Safari and IE.

by jtauber : Created on Oct. 28, 2006 : Last modified Oct. 28, 2006 : Categories python pyjamas : 0 comments (permalink)

Reddit Feeds

Although it came out in May, I just discovered that reddit (whose main site I've used for a while) provides a web-based feed aggregator along the lines of a Bloglines or Google Reader but with the added feature of their voting system. Plus it integrates nicely with the main reddit functionality. Pretty cool stuff.

Check it out at http://feeds.reddit.com/

They offer import of subscriptions directly from Bloglines but it wasn't working for me when I tried it.

by jtauber : Created on Oct. 27, 2006 : Last modified Oct. 27, 2006 : 0 comments (permalink)

Skipping Tracks

I've noticed for a while that I'm much more likely to skip over a good song on my iPod than I would if flicking through channels on the radio.

Thinking about it, I wondered if there's a certain loss of enjoyment in a song when you can hear it on demand.

But then on a trans-Atlantic flight on Monday, I noticed a similar phenomenon with playing my entire library versus just the playlist of my most highly rated. I'm far more tolerant of, say, a three-star song when listening to my entire library than a four-star song on my highly rated playlist.

So I've come up with the following formulation: The chance of skipping over a song is strongly positively correlated with the chance that the next song is at least as good.

With a "highly rated" playlist, there's a good chance the next song will be as least as good as the one I'm listening to, so I'm more inclined to skip the current song, even if I really like it.

With my entire library, if I'm listening to an "okay" song, there's a reasonable chance the next song will be one I like less, so I'm more inclined to enjoy the current song.

That's my current hypothesis, anyway. I haven't read George Zipf's work but I wonder if it relates to this.

by jtauber : Created on Oct. 25, 2006 : Last modified Oct. 25, 2006 : 4 comments (permalink)

Coordinate Systems

Long overdue post to the Poincaré Project.

When we defined manifolds back in Poincare Project: Manifolds, we pretty much defined what a coordinate system is:

Define a chart to be a continuous one-to-one mapping from an open set to R^n.

A manifold is a topological space covered by one or more charts. In other words, every point (and some open set the point is in) is part of at least one chart.

A chart provides a coordinate system and the coordinates of a point on a manifold are just the components of the point in R^n that the point on the manifold maps to in that chart.

So one way of thinking about coordinates is that they are tuples of real numbers that identify points on a manifold.

But it is important to note that coordinate systems are continuous. If you range one coordinate over a subset of its possible values, keeping any other coordinates constant, then you won't just get a random set of points, you'll get a continuous curve.

Note also that, although we often think about latitude and longitude as providing a coordinate system for the two-dimensional sphere, this single coordinate system breaks down at the poles. The north and south poles don't have a defined longitude. This doesn't pose a problem for either the latitude / longitude coordinate system or the manifold-ness of the sphere because (a) the latitude / longitude system works fine everywhere but the poles; (b) there is nothing wrong with a manifold requiring multiple overlapping coordinate systems to cover all its points.

To make this clearer, consider an even simpler example: the one-dimensional sphere, or circle. We could just map the points on the circle to [0, 1) but then we would get a discontinuity back at 0. So we have to use multiple overlapping coordinate systems:

Here we have a red coordinate system which covers part of the (black) circle and a blue coordinate system which covers a different but overlapping part. For every point, there are coordinates for that point in at least one system and the system is continuous at that point. I've arbitrarily ranged the two coordinate systems from 0 to 1 but any continuous parameterisation of the coordinate curve would work.

Next we will reintroduce the notion of a metric defined in terms of coordinate systems.

UPDATE: next post

by jtauber : Created on Oct. 22, 2006 : Last modified Aug. 9, 2007 : Categories poincare_project : 0 comments (permalink)

Users Can't Change OS X Password Using passwd

I've previous mentioned I've got a new machine for pyworks.org.

Besides the problem that Trac doesn't work on Python 2.5, the other problem is the users I've created accounts for can't change their passwords.

I created the accounts with niload, just like I did on the older machine. But when people try to login and change their password, 'passwd' asks them for the old and new passwords and then just exits with 'Sorry'.

I can't see anything obvious in netinfo and no amount of Googling so far has turned anything up.

Any ideas under what circumstances passwd will refuse to change a user's password?

NOTE: It's not a problem with the password itself. If I log in as myself, I can change my password but if I log in as other user and try to change their password to the same one I used for my own account, passwd exits with 'Sorry'.

by jtauber : Created on Oct. 20, 2006 : Last modified Oct. 20, 2006 : Categories os_x : 2 comments (permalink)

Out of Commission

I'm somewhat out of commission at the moment.

I'm spending some time in London in a new apartment and it's going to take over two weeks for BT to install a phone line (and only then can I get ADSL broadband).

So at the moment my principal source of Internet connectivity is the nearest Starbucks with WiFi which isn't conducive to most of my online projects.

Sorry about that.

by jtauber : Created on Oct. 14, 2006 : Last modified Oct. 14, 2006 : 1 comment (permalink)

New Pyworks

As I'm adding more committers to my open source projects, I decided it might be worth getting a dedicated mac mini for pyworks.org rather than sharing it with my other sites.

So I ordered another mini through macminicolo and it's up and running. I haven't switched over to using it yet, though.

A new version of subversion is out and new versions of Python and Trac are due out soon.

I think I'll wait for Python 2.5 and Trac 0.10 and then make the move.

by jtauber : Created on Sept. 15, 2006 : Last modified Sept. 15, 2006 : 4 comments (permalink)

Nelson James Performance Tonight

Just got back from a party where Nelson James performed. It was our first performance in front of an audience (as opposed to a TV studio crew) and was a lot of fun. We played three songs, Noise, When You're Holding Me and the original piano version of You Me Us We (a dance version of which Nelson and I recently finished recording at the soundbaker studio with Rob Agostini producing).

If we had a drummer and bassist to occasionally back us, I think we could do a lot more of our songs, as well as a few covers. Regarding the latter, I can now play Ben Folds Five's 'Underground' and totally annoy my family with how often I play it :-)

by jtauber : Created on Sept. 9, 2006 : Last modified Sept. 11, 2006 : 4 comments (permalink)

Surge in Poincare Bookmarking

Prior to this month, about 5 people had bookmarked my Poincare Project on del.icio.us. Then in the last week, 80 people have bookmarked it!

I better get back to working on it! :-)

UPDATE (2006/09/09): The source of recent interest seems to be a post to Ars Mathematica and a post to reddit. Not sure which came first but the former lead to a couple of hundred hits and the latter a couple of thousand.

by jtauber : Created on Sept. 8, 2006 : Last modified Sept. 9, 2006 : 0 comments (permalink)

French Translation of Pyjamas Website

In a first for me, I got an offer to translate one of my open source project sites into another language. So thanks to Gerard Labadie, http://pyjamas.pyworks.org is available in French as well as English.

by jtauber : Created on Sept. 5, 2006 : Last modified Sept. 5, 2006 : Categories pyjamas : 1 comment (permalink)

Poincare Update

I do plan to get back to writing about the mathematics behind the Poincaré Conjecture. But I thought it remiss of me not to mention here the recent developments stemming from Grigory Perelman being awarded and declining the Fields Medal for his solution.

You can read more about it here:

• Maths genius declines top prize (BBC)
• MANIFOLD DESTINY: A legendary problem and the battle over who solved it. (New Yorker)

Meanwhile I'll get back to the mathematics of it. I think the next installments will be about coordinate systems and the notion of a metric on a manifold.

UPDATE: next post

by jtauber : Created on Sept. 5, 2006 : Last modified Sept. 5, 2006 : Categories poincare_project : 2 comments (permalink)

Update: Quisition

I had thought my flashcard site, Quisition would be in open beta by now. Here's what happened: I was underwhelmed by the interest in the private beta and got somewhat demoralized.

The good news, however, is I'm motivated again and want to just add a few more features before going to open beta. Stay tuned either here or on the Quisition announcement feed. If you want to join the private beta right away, you are more than welcome - just email me.

by jtauber : Created on Aug. 28, 2006 : Last modified March 10, 2007 : Categories quisition : 0 comments (permalink)

Pyjamas Now Supports Browser-Specific Code

Thanks to Willie Gollino, pyjamas now supports browser-specific code. It might almost be ready for a 0.1 release soon!

by jtauber : Created on Aug. 19, 2006 : Last modified Aug. 19, 2006 : Categories python pyjamas : 1 comment (permalink)

Update: Music

With my frequent trips away, it's no surprise that Nelson Clemente has been focusing on his solo career.

Check him out at http://nelsonclementemusic.com/ and, if you like his stuff, help spread the word!

That's by no means the end of Nelson James, though. Our pop duo lives on and as well as eventually getting back to recording stuff together, some of my compositions will make their way on to Nelson's solo album(s).

In fact, in a few days, I'll be meeting with Rob Agostini, who produced Nelson's first two solo songs, and we'll work on a new recording of a Nelson James favourite, You Me Us We.

Nelson and I have also started working on a music video which I'll be producing, directing, photographing and editing.

by jtauber : Created on Aug. 8, 2006 : Last modified Aug. 8, 2006 : Categories record_producing_and_engineering nelson_james : 0 comments (permalink)

Back from ALI and COLING-ACL

I had expected to blog more during the last two weeks that I've been attending linguistics conferences but it didn't work out that way.

The week before last, I was in Brisbane at the Australia Linguistics Institute. My main motivation for going was that my PhD supervisor, Professor Andrew Spencer, was teaching a course there and so it was a great opportunity to finally meet face to face. I was explaining to him what I planned to do in my thesis and about a quarter of the way through, he stopped me and said: "there, that's your PhD thesis" :-)

Last week, I was in Sydney for the combined COLING-ACL conference on computational linguistics and natural language processing. Things have changed a bit in computational linguistics since I was an undergrad. In particular, it's a lot more generic machine learning and a lot less linguistics now. Researchers were boasting how good precision and recall scores they were getting "without any linguistic cleverness". I learnt a lot, though, and met some good people. I have a lot of new ideas for analyses I can perform on the Greek New Testament corpus too.

by jtauber : Created on July 24, 2006 : Last modified July 24, 2006 : Categories linguistics phd : 0 comments (permalink)

Pronunciation Field in Application Form

Last night I joined the Linguistics Society of America.

The online form had a field I thought was cute: how, described in the International Phonetic Alphabet, I pronounce my name.

I entered ʤæɪmz tʰæʊbɘ.

It just occurs to me looking at it now that, although it's a fairly broad transcription, anyone who uses it to pronounce my name will temporarily be taking on an Australian accent :-)

by jtauber : Created on July 8, 2006 : Last modified July 8, 2006 : Categories linguistic_observations : 0 comments (permalink)

Update: pyjamas

Thanks to a contribution from Willie Gollino, pyjamas is moving forward nicely. The dynamic table example from Google still isn't fully ported, but Willie has a nice grid example which is now checked in to the trunk.

In updating the unit tests to pass after his changes, I've been writing a little reporting tool that shows source code coverage, which tests pass and diffs between output and desired output when tests fail.

I plan to generate a report regularly on the website. Eventually, it might be nice to integrate the report as a Trac plugin.

by jtauber : Created on July 5, 2006 : Last modified July 5, 2006 : Categories python software_craftsmanship pyjamas trac : 2 comments (permalink)

Update: PhD

I was officially supposed to start on April 24th but I didn't receive the enrollment form until after that date (and after I'd left for the US). By the time I got the form, sent it to the UK, got details of where to wire the fee, etc, it was June. But as far as I know, I'm now officially enrolled.

The term ended June 30th so I guess I officially missed this term and am now on summer break before I've even started :-)

However, my supervisor, Professor Spencer, is running a course at the Australia Linguistics Institute in just over a week so my sister, Jenni, and I are flying to Brisbane to attend the Institute before flying down to Sydney to attend COLING.

Not only will Prof Spencer's course at ALI be a nice foundation for my PhD research, it will also be the first opportunity we've had to meet face-to-face.

by jtauber : Created on July 1, 2006 : Last modified July 1, 2006 : Categories linguistics phd : 1 comment (permalink)

Update

June has probably been my biggest writing drought since I started blogging—mostly because of helping lead a major software release at work. The good news is that mValent Integrity 4.0 has gone gold. I'm also on my way back to Australia.

Both these things mean you can expect more posts soon. I have a lot of updates to give so I'll do a post per project over the next couple of weeks.

Incidentally, this is my first post on my new 17" MacBook Pro. I'm loving the speed and screen size increase over my 12" PowerBook.

by jtauber : Created on June 30, 2006 : Last modified June 30, 2006 : 0 comments (permalink)

Apple Store Woes

I wanted to buy a new MacBook Pro while here in the US but I can't buy it from the online store. The US store won't accept an Australian billing address and the Australian store won't ship to a US address.

Today, I went into the Apple Store nearby but was told they only sell the default configuration (I want more memory and the faster drive) and for anything else I should go to the online store.

UPDATE: Just got off the phone with Apple. Telephone sales has the same problem with billing country vs shipping country but the guy told me I could pay by wire transfer so I've now been able to place my order.

UPDATE (2006-06-23): The estimated delivery in US was after my departure date, so I rang Apple a couple of days ago to switch to two-day shipping. However, instead of bringing the delivery date closer, it got pushed out even further because, after changing the shipping method, the estimated ship time got postponed six days. I rang Apple last night and they assured me it would ship sooner than that and, in fact, within the next 12 hours. Sure enough, when I woke up this morning, it had shipped from Shanghai.

by jtauber : Created on June 17, 2006 : Last modified June 23, 2006 : Categories mac : 0 comments (permalink)

György Ligeti Dies

György Ligeti, perhaps my favourite 20th century composer, died earlier this week.

Like many people, I was introduced to the music of Ligeti in Kubrick's 2001: A Space Odyssey. I still remember pouring over scores of his Requiem, Lux Aeterna and Atmosphères as a high school student. He inspired my composition Nebula from that period, which is the only composition of mine so far to be played on the radio. The movement from his Musica Ricercata used in Kubrick's Eyes Wide Shut is one of the most chilling uses of music in film.

I find myself saddened that I will never get to meet the man.

by jtauber : Created on June 15, 2006 : Last modified June 15, 2006 : 1 comment (permalink)

The apostrophe in Hawai'i

Previously, I've talked about the scifi/fantasty love of the apostrophe and how, in most cases it's meaningless but in some cases can be useful in separating vowel sounds.

It certainly looks cool which is why I use it in the word Hawai'i where I thought it made sense to separate the diphthong ai from i. In printed (Ancient) Greek you'd similarly mark the separation with a diaeresis: Hawaiï.

My girlfriend is in Hawai'i at the moment and, on the phone, I told her that I like to spell it with an apostrophe. "Oh," she said, "they always spell it that way here".

Turns out the reason is that it is pronounced as a glottal stop and the glottal stop in many Polynesian languages is distinctive: its existence or absence changes the meaning. So "Hawaii" is a different word to "Hawai'i".

Also, it's not an apostrophe, it's actually called an 'okina and is ʻ or Unicode U+02BB which is more like an opening 6 quote and may or not work in your browser.

by jtauber : Created on June 4, 2006 : Last modified June 4, 2006 : Categories linguistic_observations : 0 comments (permalink)

The L Bug in MSN Messenger

I was IMing with my sister Leonie when MSN messenger beeped and refused to display what she had just written to me. I asked her to repeat it. Beep again. Repeat. Beep again.

I got her to describe what she'd just typed and it turned out it was the word 'netball'.

Why would 'netball' cause MSN messenger to freak out?

Well, after about half-an-hour of trying various things, we narrowed down the bug to any time a lower-case L ends the line.

It works fine if I type it to her but not her to me. She's on Windows, I'm on Mac so it might be a bug in the Mac client. I've never noticed it before, though. Perhaps not many lines in an IM end with lower-case L.

by jtauber : Created on June 3, 2006 : Last modified June 3, 2006 : 4 comments (permalink)

Poincare Project

Last night I went through the old Poincare Project posts from before Leonardo had categories, and put them in the right category. I then patched Leonardo to sort them by path.

The end result is the the Poincare Project page now lists all my posts to date, in order.

I'll get back to posting on the topic real soon now.

by jtauber : Created on May 29, 2006 : Last modified May 29, 2006 : 0 comments (permalink)

Energy Drinks

Energy drinks reduce the ability to sleep but not the desire. So you still feel tired but there's nothing you can do about it.

by jtauber : Created on May 29, 2006 : Last modified May 29, 2006 : 2 comments (permalink)

Deliciously Popular

I just noticed I have 3 of the top 10 most popular python links on del.icio.us. Woohoo! If only I'd posted my Sudoku solver as well :-)

Funny thing is, one of them calls me Joshua Tauber—I guess because of Joshua Tauberer.

UPDATE (2006-05-29): 3 in top 5 now :-)

by jtauber : Created on May 29, 2006 : Last modified May 29, 2006 : 0 comments (permalink)

pyjamas Update

Making good progress with pyjamas

As of @32 it now is possible to cd into examples/helloworld where there is a lone Hello.py:

import ui
class Hello:
     def onModuleLoad(self):
         b = ui.Button("Click me")
         ui.RootPanel().add(b)

and type:

python ../../builder/build.py Hello

and have all the Javascript and HTML be generated in the output directory.

Also, the mailing list hit the 50 mark today! And I'm on a #pyjamas channel on irc.freenode.net

by jtauber : Created on May 27, 2006 : Last modified May 27, 2006 : Categories python pyjamas : 0 comments (permalink)

Summer of Code Projects Announced

I'm delighted to announce that Ryan Forsythe's project to port Kenny Tilton's Cells to Python was accepted for the Google Summer of Code 2006 and I'll have the pleasure of mentoring it with Kenny's help.

I think Cells will be a wonderful contribution to Python.

Picking the projects for Python was very difficult as we ended up with only 25 slots to fill from 186 valid submissions. You can see the list of PSF SoC projects on python.org. Note that some individual open source projects in Python were mentor organizations in their own right so there are more Python-related projects being done.

I think next year, I might apply for one of my projects to be a mentoring organization because there was some post-voting discussion that really PSF should focus on projects that directly relate to Python the language rather than projects that just happen to be written in Python.

by jtauber : Created on May 25, 2006 : Last modified May 25, 2006 : Categories python summer_of_code pycells : 0 comments (permalink)

Primitive Python Version of GWT Working

I'm pleased to announce that, after a very busy weekend and one or two weeknights, I've successfully built a Python equivalent to the Google Web Toolkit (GWT) that can handle half the Hello World example.

It sounds small but the pieces are largely all there in a primitive state:

• a Python-to-JavaScript translator
• Python datatypes
• UI widgets written in Python
• boiler plate HTML

Now it's just a case of incrementally improving each of these areas.

You can see the result in revision 19 at:

http://pyworks.org/svn/py-gwt/hello-experiment/

Join the mailing list if you want to get involved in any way.

UPDATE (2006-05-26): The project now has a name and a website: pyjamas

by jtauber : Created on May 24, 2006 : Last modified May 26, 2006 : Categories python google ajax pyjamas : 14 comments (permalink)

SubEthaEdit Release and Bug Fix Announcements

Version 2.5 of SubEthaEdit, my favourite non-Emacs text editor on OS X, has just been released.

I found out because their bug tracking system emailed me to let me know they'd fixed a bug I submitted.

Cleverly, the bug tracking system didn't email me when it was actually marked as fixed (which wouldn't help me as it's a commercial product and I don't have access to nightly builds) but rather it emailed me when the first release that fixed the problem came out—a nice email saying there's a new release and that it fixes my bug.

I think that's a cool feature for a bug tracking system.

by jtauber : Created on May 23, 2006 : Last modified May 23, 2006 : Categories software_craftsmanship : 2 comments (permalink)

Python Equivalent to Google Web Toolkit

The Google Web Toolkit looks cool. Now we know how they do it.

You write your front end in the Java programming language, and the GWT compiler converts your Java classes to browser-compliant JavaScript and HTML.

A couple of weeks ago I was thinking about a similar (at a very high level) approach in Python. But now that we have something to imitate, anyone interested in trying to build a more specific Python equivalent? Portions of the GWT are open source and nothing in the license prohibits reverse engineering as far as I can tell.

I'll set up a mailing list for interested people.

UPDATE: Mailing list available at http://pyworks.org/mailman/listinfo/py-gwt

UPDATE (2006-05-23): Now see Primitive Python Version of GWT Working

by jtauber : Created on May 17, 2006 : Last modified May 24, 2006 : Categories python google ajax : 7 comments (permalink)

Class Definitions Inside Functions

For a while, I've been defining functions in Python that define other functions and return them, taking advantage of lexical scoping and the first-class status of functions:

def foo(x):
    def bar(y):
        return x + y
    return bar

(yes, I realise you can also do this with a lambda expression)

But it all of a sudden occurred to me that you can probably define parameterised classes within functions and return them. Sure, enough, you can:

def foo(x):
    class bar:
        def __init__(self, y):
            self.z = x + y
    return bar

So foo isn't a factory producing objects, it's a factory producing classes.

This probably isn't news to most of you, but I think it's pretty cool that this works! Looking back, I can think of heaps of times I've wanted to parameterise classes and this would have been perfect.

by jtauber : Created on May 14, 2006 : Last modified May 14, 2006 : 4 comments (permalink)

Python Templates

Back in 2003, I was playing around with building templates in Python by taking advantage of a combination of dictionary-based string substitution and the ability to late bind dictionary values using __getitem__.

I posted some graded examples to the Python Web SIG at the time and tonight I dug them up and formatted them into HTML with colour syntax highlighting:

http://jtauber.com/2006/05/templates.html

UPDATE (2006-05-19): One of my Pythonista heros, Ian Bicking, suggests an alternative approach which I like a lot.

by jtauber : Created on May 13, 2006 : Last modified May 19, 2006 : Categories python : 3 comments (permalink)

Summer of Code

There were no applications for Leonardo or Demokritos projects but it looks like I'll get to mentor a new project that I'm very excited about. I don't want to say anything specific until it's officially announced but it should be a great new addition to Python.

If people are still interested in doing a Leonardo or Demokritos project, independent of SoC, just let me know - there's plenty of cool stuff to do.

by jtauber : Created on May 12, 2006 : Last modified May 12, 2006 : Categories python summer_of_code leonardo demokritos : 1 comment (permalink)

Greek Lesson

Last night's Greek Lesson went well. We went through the 24 individual letters of the Greek alphabet and the combinations ει and ου.

To prepare the lesson, I ordered the letters into 5 categories of roughly increasing difficulty for readers of the Latin alphabet. I then wrote a program that, for each category, generated up to twenty word forms in John's Gospel that (a) had a letter from the category being taught; and (b) only had letters from that category or a previous one.

I think it turned out to be a great way to learn the letters because it didn't overwhelm them too much at the beginning. It still wasn't easy, though. It's sometimes hard to remember just how "foreign" some of the letters seem when you first learn them and in some cases how misleading.

One thing I learnt last night is that Americans (or at least the ones I was teaching) don't use 'revise' and 'revision' to refer to reviewing material, for example before a test. In Britain and Australia one would say 'have you revised for the test yet' or 'I have a test tomorrow so I need to go home and do some revision'. In America, it appears those terms only mean their other sense of making a change/improvement.

Of course, one might argue that a Brit or Australia means 'change/improve my understanding of the subject' but it was still interesting that my use of the term was odd to the Americans.

Oh, and thanks to Tim Wegener, who, although not part of my course, read through the material for last night's lesson beforehand and had a wealth of wonderful questions about the history of the Greek language.

by jtauber : Created on May 10, 2006 : Last modified May 10, 2006 : Categories linguistic_observations new_testament_greek read_john : 2 comments (permalink)

Unit-Testing the Brain

I recently bought The Reasoned Schemer by Daniel Friedman, et al, being a big fan of The Little Schemer and The Seasoned Schemer (A Little Java, A Few Patterns didn't grab me in the same way).

The Reasoned Schemer teaches logical programming in a functional programming paradigm. Of course, it's written in the same question / answer style as the other books—the book asks you a question that you may or may not know the answer to and then gives you the answer. It then asks another question and gives the answer and so on. There's no other content than these question / answer pairs other than a handful of "laws" and "commandments".

The questions cover a range of cases to make sure you understand the subtleties and edge-cases. You have to mold your mind so that it gets the right answer to one question and then refine your thinking further if you can't then handle the question that follows. Eventually, the questions have handled enough cases that you really grok what's going on.

It occurs to me that this style is basically a set of Unit Tests for the Brain.

As a really simple example, here are the first three pairs from chapter 7 which define what a 'bit' is in the context of the rest of the chapter:

• Is 0 a bit?
• Yes.
• Is 1 a bit?
• Yes.
• Is 2 a bit?
• No. A bit is either a 0 or a 1.

That's just a unit test for your brain's concept of what a bit is. It's Test-Driven (Brain) Development.

by jtauber : Created on May 6, 2006 : Last modified May 6, 2006 : Categories books : 5 comments (permalink)

Teaching New Testament Greek

I'm teaching New Testament Greek to a small group and tonight was our first lesson. I just talked about the history of the Greek language and outlined the (I think) novel approach I'm taking to this course.

Basically, we'll be learning inductively but with a graded series of text fragments from John's Gospel generated algorithmically to prioritize learning the words and word forms that will, in turn, mostly quickly enable reading of more text fragments (similar to the problem posed in my programming competition).

We'll still be covering traditional grammar but it will come after the grammar points have been seen in real texts a few times. There'll be a focus on reading and learning inflected forms first (and always in the context of a clause) and only abstracting lemmas and paradigms after the fact. This far more closely resembles how first language acquisition works and should lead to much quicker intuitive understanding of the language.

This is essentially an alpha test but, as a couple of the guys are remote, I'm trying to do as much via email and Web as possible and so, if all goes well, I might offer this to a broader audience online at some stage.

I'll post updates as things progress.

by jtauber : Created on May 5, 2006 : Last modified May 5, 2006 : Categories read_john graded_reader : 4 comments (permalink)

lighttpd and launchd

On a couple of occasions, I've noticed lighttpd silently dying on my remote Mac Mini that serves up a bunch of my sites including Quisition. I was switching hemispheres earlier in the week and so didn't notice for days. So I finally decided to get around to learning how to use launchd.

Turned out to be very simple.

I previously manually started lighttpd with:

sudo /usr/local/sbin/lighttpd -f /usr/local/www/lighttpd.conf

To start it (and keep it running) using launchd, I created a file:

sudo pico /Library/LaunchDaemons/net.lighttpd.plist

with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" 
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>net.lighttpd</string>
    <key>OnDemand</key>
    <false/>
    <key>Program</key>
    <string>/usr/local/sbin/lighttpd</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/local/sbin/lighttpd</string>
        <string>-f/usr/local/www/lighttpd.conf</string>
        <string>-D</string>
    </array>
</dict>
</plist>

(note the extra -D option) and told launchd about it with:

sudo launchctl load /Library/LaunchDaemons/net.lighttpd.plist

Just for fun, I tried killing lighttpd and launchd had dutifully restarted it before I had time to type 'ps aux'

by jtauber : Created on April 29, 2006 : Last modified April 29, 2006 : Categories os_x quisition lighttpd launchd : 0 comments (permalink)

Summer of Code 2006

I'm delighted to be a mentor again in Google's Summer of Code.

Although I can't guarantee acceptance, if people would be interested in doing something with Leonardo or Demokritos, I'm happy to help them come up with a project to do. I'm also open to mentoring other Python-related ideas.

Email me if you're interested.

by jtauber : Created on April 28, 2006 : Last modified April 28, 2006 : Categories python summer_of_code leonardo demokritos : 1 comment (permalink)

Two Browsers

Sam Ruby has a nice post on the cross-browser obstacles he's recently encountered.

The first two are exactly the problems I had with getting Quisition working on IE. The very first one had me stumped for ages even though it's dead simple (following the inverse law of bug complexity).

I'm still looking for more closed beta testers for Quisition. Just email me if you're interested in trying out online flashcards with clever spaced repetition.

by jtauber : Created on April 19, 2006 : Last modified April 19, 2006 : Categories quisition web_design : 1 comment (permalink)

The Wealth of Networks and Non-markets

I've just started reading Yochai Benkler's book, The Wealth of Networks: How Social Production Transforms Markets and Freedom online, although I will probably pick up a printed copy at some stage.

It's fascinating so far but I was immediately confused by Benkler's frequent use of the term "non-market" which, in context, seems to suggest he has a much narrower sense of what the "market" is than I've come across before.

For example, consider the following quote (from the first chapter summary on the book's wiki):

Freedom and justice is best achieved through a combination of market action and private, voluntary (thought not necessarily charitable) nonmarket action. The state in this theory is a relatively suspect actor.

I'm not sure what he means by "market" if private, voluntary action is "nonmarket".

by jtauber : Created on April 16, 2006 : Last modified April 16, 2006 : Categories economics books : 3 comments (permalink)

Getting less to work with UTF-8

I've been working with UTF-8 files on the 'nix command-line for years, most recently on OS X.

I've been frustrated that things like cat and head work fine once Terminal is set to display UTF-8 but less doesn't seem to recognize UTF-8 even in that case.

I finally got around asking Google for a solution.

20 seconds later, I found it:

export LC_CTYPE="en_US.UTF-8"

via Notes on UTF-8 and locales

Boy do I feel stupid for not just looking it up earlier!

Anyway, maybe someone else will find that useful to know :-)

by jtauber : Created on April 16, 2006 : Last modified April 16, 2006 : 3 comments (permalink)

Python Tuples are Not Just Constant Lists

Greg Wilson is suggesting things Python 3000 could leave out and suggests tuples.

In the comments, Phillip Eby holds him to task for the assumption that tuples are just constant lists:

Tuples are not constant lists -- this is a common misconception. Lists are intended to be homogeneous sequences, while tuples are hetereogeneous data structures.

I think it was years into my use Python that I realised this and stopped thinking about them as just constant lists. It was a powerful revelation for me.

So while I agree with Greg that many (most?) programmers don't understand the distinction, I think they are missing out and that we'd be better off improving the way lists and tuples are documented than try to conflate what is, in my opinion, a very useful distinction.

One way I'd express it (in addition to Phillip's quote above) is that the index in a tuple has an implied semantic. The point of a tuple is that the i-th slot means something specific. In other words, it's a index-based (rather than name based) datastructure.

This notion of 'tuple' is very important in relational algebra (as Phillip also points out) and so I've been thinking about it in the context of relational python too.

When I started playing around with relational python (which I need to get back to blogging about), it occurred to me that it might be useful to have the notion of a tuple whose slots could additionally be named and then accessed via name. I implemented it that way in Basic Class for Relations.

by jtauber : Created on April 15, 2006 : Last modified April 15, 2006 : Categories python relational_python : 37 comments (permalink)

Fire Someone Today

Even if you're not interested their products, Logos Bible Software is a fascinating company on a number of levels. From the look behind the scenes you get from their blog to their innovative community pricing model where the market votes on the product priorities and pricing before production even starts, Logos is an interesting company to watch and learn from.

So I was delighted last August to discover that founder and CEO, Bob Pritchett, was writing a book on practical advice for startups called Fire Someone Today. Bob kindly sent me a PDF draft and I loved it—entertaining but also honest and very insightful.

Well, the book is now available from Amazon and, in typical Bob Pritchett style, Logos is offering $20 credit on their online store for anyone who buys the book from Amazon by midnight tomorrow. A nice deal given the book costs less than $10.

Even if you have no interest whatsoever in Bible software, it's a book worth taking a look at if you're interested in startups and entrepreneurship.

by jtauber : Created on April 15, 2006 : Last modified April 15, 2006 : Categories entrepreneurship books : (permalink)

Get Paid for Upgrading Aperture

I commented to my friend James Marcus recently that I liked Aperture but it was definitely overpriced.

Well, Apple has just released Aperture 1.1 for $299 instead of the $499 price tag on the original.

And, in a great move, they've offered anyone who bought 1.0 a $200 credit at the online Apple Store (and it's a free upgrade).

by jtauber : Created on April 14, 2006 : Last modified April 14, 2006 : Categories photography apple : 0 comments (permalink)

Economics Precepts

Jason Fried says his favourite economic precept is 'sunk cost'.

I think sunk cost is mostly interesting because of the prevalence of the sunk cost fallacy where people say things like "I don't feel like going to the concert but I've already spent the money on the ticket so it would be a waste not to go".

This fallacy, like many in economics, comes down to not appreciating opportunity cost, particularly applied to that most precious of resources: time.

Another favourite economic precept of mine is comparative advantage. Comparative advantage is key to understanding why voluntary trade is win-win, even when one party can produce all the goods most efficiently. At its core, though, comparative advantage is a corollary to opportunity cost.

Yet another favourite economic precept of mine is Frédéric Bastiat's broken window fallacy where people say things like "at least this natural disaster will be good for the construction industry". But again, the broken window fallacy is about (not) understanding opportunity cost.

So I would have to say opportunity cost is my favourite economic precept because it is foundational to so many other important precepts.

Of course, I've mentioned before on this blog that I also think marginal utility and the subject theory of value are very important to understand.

If I made a list of "100 things everyone should know" I think I would put all the precepts mentioned here on it.

by jtauber : Created on April 12, 2006 : Last modified April 12, 2006 : Categories economics : 0 comments (permalink)

Stats and Spam

When I commented on my January stats I said

Looking at my web stats, it appears that last month I had almost 100,000 visits (97,571) from almost 20,000 distinct IPs (19,484) averaging almost 10,000 hits/day (9,801).

In February I had a slight decrease in visits (93,441) from slightly more distinct IPs (19,528) and broke 10,000 hits/day (10,826).

However, I have very mixed feelings about March: 129,719 visits and 17,265 hits/day. I should be delighted (a 60% increase in hits month-over-month!) but I can't help but think most of the increase is meaningless (and possibly malicious).

Especially when I had 10,980 hits from just one IP address (80.77.80.46) in March accessing two blog entries repeatedly.

Certainly the tripling of the number of bytes served from the start of the year until I added the maths CAPTCHA is directly attributable to comment spam.

But there also seems to be a relationship between which web pages got hit with comment spam and which are now getting accessed disproportionately by the same IP addresses over and over again.

by jtauber : Created on April 3, 2006 : Last modified April 3, 2006 : Categories this_site spam : 0 comments (permalink)

Quisition Limited Beta

I've been saying since last year that a limited beta of my flashcard site, Quisition, would be available in Q1 2006. Well I've just made it under the wire. Email me if you are interested in trying it out. An open beta will be available some time in May.

by jtauber : Created on March 31, 2006 : Last modified March 31, 2006 : Categories quisition : 0 comments (permalink)

Subversion Keywords in LaTeX Documents

I wanted a LaTeX document I'm writing to show the Subversion keyword expansion but I couldn't work out how to do it. If I used something like $Id$, LaTeX treated it as being in math mode but if I used \$Id\$ then Subversion didn't expand it.

I finally hit the right Google search term and found $ $Id$ $ works nicely.

I'm sure there are other ways. Any ideas?

by jtauber : Created on March 28, 2006 : Last modified March 28, 2006 : Categories subversion latex : 2 comments (permalink)

Quadtrees in Javascript and CSS

Quadtrees are a data structure that involves recursively dividing squares into quarters. I like to think of them as binary trees for spatial data. Indeed, they get used a lot for spatial indexing. They also get used a lot in games (especially MMORPGs) as a way of varying the level of detail required in different areas of a map.

For a browser-based game idea I have, I want a way of selecting arbitrary regions and I wondered if a quadtree approach might work for the UI. So I then wondered if quadtrees could be displayed and manipulating using CSS and Javascript.

It took me a little while to settle on the best way to arrange four consecutive div elements into a 2x2 arrangement and it was quite frustrating that adding borders to the divs threw off the layout regardless of what approach I took. But I'm very happy with the end result.

It took even longer to sort out the manipulation of CSS via Javascript as I'm a novice in that area. But again, it all turned out nicely, even better than I expected.

You can see a demo of the result. Select "divide" mode and clicking on a square will divide it into four. Select "select" mode and clicking on a square will toggle whether it's part of the selection or not.

It works in Safari and Firefox. I can't be bothered testing it in IE :-)

by jtauber : Created on March 24, 2006 : Last modified March 24, 2006 : Categories games javascript css : 6 comments (permalink)

Switched over to lighttpd

I just switched a bunch of my sites over to running on lighttpd including http://morphgnt.org/, http://leonardo.pyworks.org/ and http://www.quisition.com/.

It took me a little while to work out how to translate my ScriptAlias directives in Apache to lighttpd (hint: configure mod_alias to map the request path to the CGI script then mod_cgi to recognize files ending in certain characters as being CGI scripts)

The only problem I now have is I've killed anonymous SVN access on pyworks.org because I was previously serving it up via Apache. I'm still investigating alternatives to running Apache just for this purpose.

by jtauber : Created on March 20, 2006 : Last modified March 20, 2006 : Categories web lighttpd : 2 comments (permalink)

Account Management Patterns

On the weekend, I drew some diagrams describing the account management sub-system I had written for Quisition, partly to see the patterns abstracted from the particular implementation.

Here's the login pattern:

Elliotte Rusty Harold recently wrote about the problems with using GETs for confirmation.

I wanted account signup to involve being sent an email to ensure the user had given a legitimate email address, but cognisant of the issues Rusty raises, I made the email received on signup link to a further form the user then has to submit to truly activate the account:

I originally had the "forget password form" directly resetting the password, but then I realised someone could maliciously enter the email address of another user to reset their password. Not a security issue so much (the new password goes to the right person) but it's a nuisance for the person if they didn't request the reset.

So I adopted an additional pattern where an email is sent which then takes the user to a reset password form:

In both cases, the URI in the email includes a hash in the parameters so the GET that leads to the form can't be faked.

by jtauber : Created on March 20, 2006 : Last modified March 20, 2006 : 2 comments (permalink)

Emacs, Unicode and Greek on Mac OS X

Ulrik Petersen pointed me to How to use EMACS with Unicode Greek (polytonic Greek (multiaccented) included) and LaTeX.

"I can go back to using Emacs!" I thought to myself (actually, I probably typed it out loud to Ulrik over IM)

All that remained was to find a more up-to-date OS X build of Emacs. OS X comes with 21.2 but the greek.el above requires 21.3.

My initial Google searching found that a lot of Emacs for OS X work ended in 2003.

Then I stumbled across this: Carbon Emacs.

Emacs 22 for Tiger (with Universal Build).

The anti-aliasing is beautiful and greek.el works a charm.

Now to dig up my old .emacs file...