Archive for: July, 2007

Friday Random Ten, July 13th

Jul 13 2007 Published by under Music

1. **Marillion, "If My Heart Were a Ball It Would Roll Downhill"**: Very neat track from
one of my favorite neo-progressive bands. Catchy, but with lots of layers.
2. **Mandelbrot Set, "Constellation of Rings"**: math-geek postrock. What's not to love?
3. **The Police, ;Every Breath You Take"**: I've always been a fan of the Police. But
what I like most about this song is how often it's been used by clueless people. I've
heard this at multiple weddings, where the couple thought it was a beautiful romantic
song. If you listen to it, it's anything but romantic. It's actually a rather evil
little song about a stalker: "Every breath you take, every vow you break,
every smile you fake, I'll be watching you... Oh can't you see, you belong to me?"
How can anyone miss that?
4. **Naftule's Dream, "Speed Klez"**: John Zorn-influenced klezmer mixed with
a bit of thrash. Insane, but very very cool. Thrash with a trombone line!
5. **Jonathan Coulton, "Todd the T1000"**: Sci-fi geek pop. It's a catchy little pop
song about trading in your old robot for a new one which turns out to be a
6. **Hamster Theater, "Reddy"**: A short track from a great band. Hamster Theater
is a sort-of spin-off from Thought Plague. It's a bit more traditional than
what you'd hear from TP; still very dissonant, sometimes atonal, but more often
closer to traditional tonality and song structure. This track is a short instrumental
featuring an accordion solo.
7. **Transatlantic, "Mystery Train"**: great little song. It's a track by one of
those so-called supergroups; Transatlantic is a side-project formed by members of
Marillion (bassist Pete Travawas), Dream Theater (drummer Mike Portnoy), Spock's Beard (singer Neil Morse), and the Flower Kings (guitarist Royne Stolt). In general, these
supergroups have a sort of shaky sound. These guys are *great* together; it sounds
like they've been playing together for years: they're sharp, there's a great interplay
between the different instruments, it's all incredibly precise. I've heard that the
music was written in advance mainly by Morse, but even with polished music pre-written,
it's got a great sound, and you can here the distinctive musical voices of each of the
8. **Godspeed You! Black Emperor, "Antennas To Heaven"**: It's Godspeed - which means
that it's brilliant post-rock. This starts off with a very rough recording of a very
old-timey folkey tune, and uses it as a springboard into a very typical God-speed
9. **The Flower Kings, "Devil's Playground"**: more neo-progressive stuff. This is an
incredibly long piece (25 minutes), very typical of Roine Stolt's writing. It's not
the sort of way-out-there kind of thing that you'd hear from, say, King Crimson; it's
very structured, very melodic, but put together more in the structure of a symphony
(theme, development, restatement) than the typical ABACAB structure of a rock song.
10. **Porcupine Tree, "Sleep Together"**: a brilliant song by yet another neo-prog
band. Very odd... a strange electronic pulse drives the entire song; but it starts
off as a very quiet song with this electronic pulse giving it a tense feel. Then
the percussion comes in, and shifts your sense of the rhythm... And then it gets
to the chorus, which is big and loud, and features a full string section. Strange,
but wonderful.

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Fractal Borders

Jul 12 2007 Published by under Fractals

Part of what makes fractals so fascinating is that in addition to being beautiful,
they also describe real things - they're genuinely useful and important for helping us to
describe and understand the world around us.
A great example of this is maps and measurement.

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57 responses so far

Fractal Woo: Video TransCommunication

Jul 11 2007 Published by under woo

This is a short one, but after mentioning this morning how woo-meisters constantly invoke
fractals to justify their gibberish, I was reading an article at the 2% company
about Allison DuBois, the supposed psychic who the TV show "Medium" is based on. And that
led me to a perfect example of how supposed fractals are used to justify some of the
most ridiculous woo you can imagine.

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The Mandelbrot Set

Jul 11 2007 Published by under Fractals

The most well-known of the fractals is the infamous Mandelbrot set. It's one of the first
things that was really studied *as a fractal*. It was discovered by Benoit Mandelbrot during his early study of fractals in the context of the complex dynamics of quadratic polynomials the 1980s, and studied in greater detail by Douady and Hubbard in the early to mid-80s.
It's a beautiful
example of what makes fractals so attractive to us: it's got an extremely simple definition; an incredibly complex structure; and it's a rich source of amazing, beautiful images. It's also been glommed onto by an amazing number of woo-meisters, who babble on about how it represents "fractal energies" - "fractal" has become a woo-term almost as prevalent as "quantum", and every woo-site
that babbles about fractals invariably uses an image of the Mandelbrot set. It's
also become a magnet for artists - the beauty of its structure, coming from a simple bit of math captures the interest of quite a lot of folks. Two musical examples are Jonathon Coulton and the post-rock band "Mandelbrot Set". (If you like post-rock, I definitely recommend checking out MS; and a player for brilliant Mandelbrot set song is embedded below.)

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An Unsolved Simple Graph Problem

Jul 10 2007 Published by under Graph Theory

One of the things that I find fascinating about graph theory is that it's so simple, and
yet, it's got so much depth. Even when we're dealing with the simplest form of a graph - undirected graphs with no 1-cycles, there are questions that *seem* like that should be obvious, but which we don't know the answer to.
For example, there's something called the *reconstruction theorem*. We strongly suspect that it's really a theorem, but it remains unproven. What it says is a very precise formal version of the idea that a graph is really fully defined by a canonical collection of its subgraphs.

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An Introduction to Fractals

Jul 09 2007 Published by under Fractals

I thought in addition to the graph theory (which I'm enjoying writing, but doesn't seem
to be all that popular), I'd also try doing some writing about fractals. I know pretty
much *nothing* about fractals, but I've wanted to learn about them for a while, and one
of the advantages of having this blog is that it gives me an excuse to learn about things that that interest me so that I can write about them.
Fractals are amazing things. They can be beautiful: everyone has seen beautiful fractal images - like the ones posted by my fellow SBer Karmen. And they're also useful: there are a lot of phenomena in nature that seem to involve fractal structures.
But what is a fractal?

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35 responses so far

Graph Contraction and Minors

Jul 08 2007 Published by under Graph Theory

Another useful concept in simple graph theory is *contraction* and its result, *minors*
of graphs. The idea is that there are several ways of simplifying a graph in order to study
its properties: cutting edges, removing vertices, and decomposing a graph are all methods we've seen before. Contraction is a different technique that works by *merging* vertices, rather than removing them.

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Graph Decomposition and Turning Cycles

Jul 04 2007 Published by under Graph Theory

One thing that we often want to do is break a graph into pieces in a way that preserves
the structural relations between the vertices in any part. Doing that is called
*decomposing* the graph. Decomposition is a useful technique because many ways
of studying the structure of a graph, and many algorithms over graphs can work by
decomposing the graph, studying the elements of the decomposition, and then combining
the results.
To be formal: a graph G can be decomposed into a set of subgraphs {G1, G2, G3, ...}, where the edges of each of the Gis are
*disjoint* subsets of the edges of G. So in a decomposition of G, *vertices* can be shared between elements of the decomposition, but *edges* cannot.

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Edge Coloring and Graph Turning

Jul 03 2007 Published by under Graph Theory

In addition to doing vertex and face colorings of a graph, you can also do edge colorings. In an edge coloring, no two edges which are incident on the same vertex can share the same color. In general, edge coloring doesn't get as much attention as vertex coloring or face coloring, but it can be an interesting subject. Today I'm going to show you an example of a really clever visual proof technique called *graph turning* to prove a statement about the edge colorings of complete graphs.
Just like a graph has a chromatic index for its vertex coloring, it's got a chromatic
index for its edge coloring. The edge chromatic index of a graph G is the minimum number of colors in any edge-coloring of G. The theorem that I'm going to prove for you is about the edge chromatic index of complete graphs with 2n vertices for some integer n:
**The edge-chromatic index of a complete graph K2n = 2n-1.**

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A Taxonomy of Some Basic Graphs

Jul 02 2007 Published by under Graph Theory

Naming Some Special Graphs
When we talk about graph theory - particularly when we get to some of the
interesting theorems - we end up referencing certain common graphs or type of graphs
by name. In my last post, I had to work in the definition of snark, and struggle around
to avoid mentioning another one, so it seems like as good a time as any to run through
some of the basics. This won't be an exciting post, but you've got to do the definitions sometime. And there's a bunch of pretty pictures, and even an interesting simple proof or two.

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