pi's New Writeups

qq (thing)

2004-10-01T04:48:30Z

QQ is the number one chinese instant messaging (IM) program. Most versions are in Chinese, but there is also an English version. It's available at im.qq.com. I'm not sure how many users it has, but according to their web site they broke 6 million simultaneous users in march 2004. In the small city I live in about 90% of my students use it.

In a lot of ways QQ is more advanced than other IM clients.

My favorite feature is sharing sounds - you can set it up so that the sound playing on one computer is sent to another. So whatever I'm playing in winamp or realplayer is automatically encoded and sent to the other person. It's a really easy way to be a DJ for your friends. I can't imagine it being that easy to share music over aim or MSN.

It's got lots of nice icons. It's got something called "QQ show" where you can pick and customize an avatar, buying facial expressions, clothes, backgrounds etc with QQ money, which you get by winning games on QQ game. …

Infinite expected value (idea)

2004-06-24T21:16:52Z

If the expected value of a bet is positive, should you do it? In other words, if you will make money on average, should you play?

How about this: A game costs 1 million dollars to play. The amount of money you get will be determined by flipping a fair coin. Your winnings depend on how many heads in a row you get. If you get a tail the game is over.
Here is the payout:

0 heads - 1$
1 head - 2$
2 heads - 4$
3 heads - 8$
4 heads - 16$
5 heads - 32$
...

If you make h heads in a row, your return is 2^h dollars.

Expected value is the sum of (the probability of an outcome * it's value) for all outcomes.

That is 1/2*1 + 1/4*2 + 1/8*4 + 1/16*8 ...
= 1/2 + 1/2 + 1/2 ...

So your expected value is infinite. However, your chances of coming out ahead in this game are less than one in a million. The thing is, even though you have a low chance of coming out ahead, if you do manage to make money, you'll make so much that…

Sell high, buy low (idea)

2004-06-03T17:50:01Z

This is another strategy used to play the stock market. First, you borrow a bunch of overvalued shares from a friend, with a promise to give them back in a while. Then you sell them. When the price goes down, you buy them back and return them to your friend. You made money.

The technical name is selling short.

Borrowing them from a friend can be accomplished by selling futures. That means that you agree to give someone a bunch of shares in the future, and they give you cash now. You could just buy the shares now and wait, but you wouldn't make any money. If you think the price will go down, wait until then. Then buy cheap and keep the rest of the money.

If you were wrong and the price goes up, you can lose a lot of money, since you are committed.

When attempting to buy low, sell high, you can't lose more money than you put in. But with sell high, buy low, you can potentially lose an infinite amount of money, since you are committed to give someone a certain amount of shares when the time comes, no matter what their price is then.

Foresight Exchange (thing)

2004-06-03T16:42:30Z

Foresight Exhange is a prediction market. Players buy "shares" in various claims with fake money, and if the claims come true, they make money. It's at www.ideosphere.com.

FX originated as a way to track pundits - who always make wild predictions but are almost never held accountable for them. If they played FX, we could look at their score in a year or two and see how accurate they were.

It is also useful to find out the concensus about various ideas. News reports make an effort to cover both sides of every story, even when the facts don't back up one side. The classic example is global warming, where a few respected scientists are quoted warning of the dangers, followed by a other scientists who happen to be employed by Big Energy who play down the dangers. If there were a related claim on FX, you can look at the price, and look at the holdings of successful players.

The most popular claim right now is Bush04, trading at about 50. The claims states that Bush will win re-…

Free bar (thing)

2002-10-08T07:05:33Z

A free bar is a bar that gives away drinks free to anyone they want, and don't accept anything in trade. They accept gifts, especially ones that relate to their operation, but none is required in order to get drinks. Free bars are pretty rare, but there were some during Burning Man 2002 - Safari Social Club to name one. They exist in contrast with barter bars, and regular bars where you have to pay.

Free bars inspire amazing feelings of gratitude, which often results in them getting gifts of more liquor, which allows them to continue operation. Also, on the bar there are usually various gifts, including food that anyone can eat. They are also great fun, because anyone you see, you can just grab and make them come over and get a free drink. Free bars usually attract great crowds of people, who are soon drunk milling around, grabbing more people and liquor.

Free bars last until they run out of liquor. Sometimes they slow down the liquor output in order to remain in operation longer.…

Boustrophedon (idea)

2002-04-12T07:44:58Z

Although most languages now are not boustrophedonic, there is at least one partial exception: Japanese. If you look at the right sides of company cars in Japan and you can read kanji, you will notice that often the name of the company on the right side is written backwards.

So for example, if the company is called say "den ki", then on the left side of the car near the front there will be "den" and towards the back there will be "ki", and that's normal. But, on the right side of the car, the company wants to have the first part of the name nearer the front of the car, so they will write it starting at the front of the car again, reading left this time. However, the left-right orientation of the kanji character itself will not be reversed.

Which brings up something pretty interesting - which level of rearrangement of a written language would be most efficient in boustrophedonic form? The simplest way would be to just use mirror versions of each letter. Next, you could use…