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This opens up entirely new uses for a projector for the nerdy crowd:

Some examples/ideas:
  * Projector tiling
  * Cheap, portable 3D Scanning
  * Real-time photo sharing (obvious)
  * Portable video-conferencing, telepresence (think projector-screen-like avatars around the screen with a tiny projector attached to each of them)
  * Pseudo-Invisibility!! (Think helmet-mounted camera, white t-shirt, dorky looking wearable projector mount)
  * Head-Mounted Projector applications (other types of invisibility, "Virtual Cockpit", freaking people out at night clubs, etc.)

I went to a talk a while ago about automatic music clustering. Basically, the researchers got a bunch of MIDIs — some classical, some pop, some jazz — cleaned them up a bit, and then used bzip2 to test them for similarity:

From memory, to test two pieces A and B, you concatenate the files to produce AA, AB, BA, and BB. Then use bzip2 to compress each concatenation. We expect AA and BB to compress well (because there are obviously big areas of similarity). If AB and BA also compress fairly well, then A and B are "close". Otherwise, they aren't. I forget what exact computation was used, but it was pretty simple.

Here's an arciel I found on the topic: http://www.ercim.org/publication/Ercim_News/enw54/ vitanyi.html.

I thought about doing that with mp3 — take two uncompressed audio files, join them together, compress with lame — but it didn't work; I think this is because mp3 is too local and unable to take advantage of bigger structures in the audio (which is obviously a design goal because you need to be able to decode on the fly).

Interesting stuff, though..

http://www.ercim.org/publication/Ercim_News/enw31/ bergamasco.htmlThis could be on the right path.

Aww, come on, at that point you might as well mention Al Gore...

There were browsers before Mosaic; only they were text-only. The transition between text-based applications and GUI-based ones is trivial and well-documented; it happened at NCSA, but it might as well have happened in New Zealand, or Germany. At the point Mosaic was created, there were already quite a few sites on the Web, or it would have been useless for Kunz et alii to build a graphical client for it -- there was a rival protocol, Gopher, developed in the US, but it was more complex and seems to have all but died out.

Finally, know that the W3C, which regulates the Web, has its copyright held jointly by three bodies: One is MIT in the US, another is the European ERCIM, and the other is Keio U in Japan. Pretty international, if you ask me.

There is (was?) a project at KTH/SiCS in stockholm with a similar concept called GeoNotes. This link is unfortunately not working right now, here is a description of the concept.

It depends on how much time you are willing to afford. A trivial algorithm is to try every (prime) number sqrt(N) to see if it divides N, if there is none, N is prime. But in practice this is too slow to let you get much beyond N ~20 digits.

Elliptic Curve Primality Proving is state of the art for general primality proofs today, try Primo which has been used to prove a 5020 digit number prime.

Integer factoring is much harder than proving primality, the current record for a GNFS factorization is a 158 digit composite, see here.

Alex