Async voice chat

It should be pretty easy to piggyback asynchronous push-to-speak voice chat over IRC or another existing chatroom system. One speech compresses a recording and transmits ASCII encoded. Tones corresponding to a partial hash of the username can identify the speaker. Those without a microphone can participate via speech synthesizer either at the source or destination... an interesting exercise might be to synthesize directly to a speech compression format. The speakers should be turned off when recording. One can click to skip an utterance. There is a text side channel for URLs, spellings.

square dissect

In a similar vein, dissect a square into two squares the same size.

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Mobile Email from a Cingular Wireless Customer http://www.cingular.com

(Solution: cut square into quarters along diagonals.)

Lissajous sundial

Can mirrors, lenses (or other static devices?) accelerate the image of the sun or shadow of it across the sky? It would be neat for a "sundial" which focuses a point of light from the sun to trace a lissajous curve, quickly enough that you can watch it move.

A very tall sundial produces macroscopically visible motion.

twofish and rijndael (aes) galois field modulo polynomials

In GF(2^8), twofish uses exponents 8 6 5 3 0. Rijndael uses 8 4 3 1 0. The latter is irreducible but not primitive.

Halfbakery: Lossy Text Compression

Halfbakery: Lossy Text Compression. Better than deleting mail, make it more and more garbled.

Falafel Sushi

I had a great food idea: falafel sushi.

In other news, it would be nice to be able to search (say with Google) for the phrase "falafel sushi" excluding results that only have "falafel, sushi" with a comma in it.

Ebay images

ebay is probably a great source of labeled images: sellers have incentive to take pictures of what they are selling and describe it in detail.

A composite of certain-sized primes

In Pari/gp

fp(upmax)=while(1,x=random(upmax);if(isprime(x),break));return(x)

a=1;for(i=1,40,a=a*fp(10^14));a

kill a process after a while

run_whatever & pid=$!

sleep 3600

kill $pid 2>/dev/null

(Incidentally, no popular web search engine gives responses for the query $! )

It might be possible to hack something using ulimit, too

delicious cache

One should try to cache or mirror all the pages bookmarked in del.icio.us

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Mobile Email from a Cingular Wireless Customer http://www.cingular.com

ean-13

Notes on EAN-13:

12 decimal digits (a 3 digit country-code or numbering-system forces a 4 digit manufacturer code; normally 2 and 5).

39.86 bits

8.48 alphabet characters.

Just how much text could fit in there with a good english language model?

quantifying brittleness

Is there a numeric measure of brittleness applicable to crystals? If you have the force being applied in precisely the correct angle, how much force or pressure is required to separate the crystal along the optimal plane?

Constructing a building one atom at a time

Using perhaps proteins can one construct a diamond or another crystal one atom at a time? Can the shape to be constructed be encoded in DNA? Can this nanotechnology be scaled to, say, produce a building shaped out of a single diamond crystal?

hibernating a process

Instead of hibernating (storing state to disk) the entire computer, it would be neat if one could hibernate (freeze) a process, storing its state to disk (perhaps PKE) to restore after a reboot, or even on another computer. One could possibly implement this in the Java framework.

Time calculator

I wish there were a calculator that handled time durations. Some expressions to evaluate:

today

today + 200 days

4 years / 37

now + (6 day)/15

17:00 - 3:15

now - 4y6mo3d7h12m18s

17june-12april

(midnight june 19th)-(7pm on 12april) in minutes

Perhaps this can be an improvement on Google Calculator.

DDOS defense

A first step in protecting against distributed denial-of-service attacks is fairly easy. A bunch of reputable internet monitoring firms/agencies get together (or even separately) publish lists of IP addresses they believe to be zombies.

Every computer, perhaps as a standard part of windows or as a antivirus software, checks its own IP address against this list. The key is not to have the list stored statically on a website (such a website would be the target of a DDOS attack) but instead use some distributed or peer-to-peer method of distributing the list, for example bittorrent, DNS, or freenet.

Fibonacci 2415

Using B1=1729088, B2=1831871846, polynomial Dickson(6), 
sigma=3239290800
Step 1 took 137598ms
Step 2 took 52834ms
********** Factor found in step 2: 
8481484594838771930389268119292044741
Found probable prime factor of 37 digits: 
8481484594838771930389268119292044741
Probable prime cofactor 
4778659403825044547766583120181669070482900352314133895851144572034118275862431169700972910183602915561356234954405228398423310326757410593640090570970332601
has 157 digits

? print(factor(fibonacci(2415)))
[2, 1; 5, 1; 13, 1; 61, 1; 137, 1; 421, 1; 829, 1; 1381, 1; 3221, 1; 8693, 1; 18077, 1; 28657, 1; 141961, 1; 186301, 1; 164967041, 1; 8288823481, 1; 588860742541, 1; 1795220677069, 1; 2441738887963981, 1; 2667297067452361, 1; 612606107755058997065597, 1; 25013864044961447973152814604981, 1; 461260622582580115020470322214561, 1; 8481484594838771930389268119292044741, 1; 6341452905360146056272600296395866384176869, 1; 660197807808925399815745309795984424904274580236856941016852839261, 1; 4778659403825044547766583120181669070482900352314133895851144572034118275862431169700972910183602915561356234954405228398423310326757410593640090570970332601, 1]

Goodstein Sequence

Goodstein Sequence -- from Wolfram MathWorld

Is the length of the goodstein sequence the fastest growing function one can imagine computing? (recursive?). The Busy-beaver functions relies on a black box of proving a turing machine non-halting, so is unsatisfying.