Wednesday, February 28, 2007

Working together

Open source software is great.   Anyone can improve the source code, add features, or just access the source code to better understand the software.  The Internet revolution has been fueled by various open source technologies.

Wikipedia is the open source software model applied to a writing a collaborative encyclopedia.  It works well.

The Oxford English Dictionary had a similar start.  From 1857 to 1928, thousands of people sent examples of word usage not in their dictionaries.  A few editors complied this into a dictionary.   Sounds pretty similar to wikipedia to me, but with more primitive tools.

Was this the first example of this model?  Do you know of other examples?  Why is it that we don't see this in more artistic fields, i.e. composing music?

Monday, February 19, 2007

Great Book

Thanks to JP for recommending this great book -- Basic Economics. I highly recommend it. A lot of the content is things I already knew, but it's full of small examples and his writing style is very engaging.

Sunday, February 11, 2007

Funny book review

I so agree with this review.   I think authors are running out of ideas for books and just fill them up with countless examples of the same thing.

Monday, February 05, 2007

A fun puzzle

Let's say there are 10 cars, each numbered 1 to 10. Each car travels at a speed equal to its index * 10mph. For example, car number 3 goes 30mph, and car 10 goes 100mph. Now, assume they are traveling in a single lane road and no passing is allowed. Each car still prefers to go at the speeds described above unless a slower car is ahead and forces the faster car to go at the speed of the slower car. So if car 3 is behind car 1, then they both travel at 10mph since car 3 cannot pass 1.

For any random distribution of cars, if someone looks at the road from above they will see different pockets of cars going together. For example, assume the cars are going in order: 5 (back), 3, 1, 7, 8, 10, 4, 2, 6, 9 (front). We have 4 pockets. 5, 3, 1 travel at 10mph. 7, 8, 10, 4, 2 travel at 20mph. 6 travels at 60mph and 9 is speeding ahead of everyone at 90mph.

Now, assume we have N cars and consider all random distributions.

Question 1) On average, how many pockets are formed?

Question 2) What's the average size of pocket?
In the example above, it's (3 + 5 + 1 + 1)/4 = 2.5

I'll reply with possible answers and also a funny story about this puzzle.