More than \(1-\frac{1}{n}\) of the circumference of a circle is colored black. Can you draw a regular \(n\)-gon on the circle with all vertices in black regions?

this is yet again problem from the book.

  1. solve assuming the black area is in finitely many disjoint intervals
  2. solve assuming the axiom of choice and not assuming anything beyond the measure of the set of black points being larger than \(1-\frac{1}{n}\).

um. I’m going to pretend like I didn’t think up question 2. but I’m kind of curious. could it really be different? anyways, here’s my solve for question 1:

Proof. Imagine a discrete version of the problem. It is trivial.

Now, if we discrete the original problem correctly we get this trivial discretized version.