Monthly Archives: November 2010

CAPTCHA arbitrage

What a world we live in. It seems there are places on this planet that are wired well enough to support internet commerce, yet where people are poor enough that solving CAPTCHAs for 50 cents per thousand is an economically … Continue reading

Posted in computing, modern life | 14 Comments

Whack-a-Rectangle

It’s been almost a year since Bill Gasarch gave us the problem of four-coloring the nodes of a 17 × 17 grid in such a way that no rectangle has all four corners the same color. (See my earlier commentary … Continue reading

Posted in computing, mathematics, problems and puzzles | 2 Comments