You have an ink stamp that is so amazingly precise that, when inked and pressed down on the plane, it makes every circle whose radius is an irrational number (centered at the center of the stamp) black.

Is it possible to use the stamp three times and make every point in the plane black?

If it is possible, where would you center the three stamps?

after all the discussion of the rational/irrational set sizes, the problem has kinda been overlooked. I like the approach that Eric started with, and I think it shows ~conceptually~ that there is a solution, but it is not really complete...

Posted by Cory Taylor on 2003-12-03 10:03:58