Richard Schroeppel asked:

Puzzle: Choose some specific ellipse, say a=2 b=1. Find any packing that has a higher packing density than circles in the plane (the simple hex packing).

A related question: Suppose we're allowed to use more than one shape of ellipse, as long as all of them have the same area. Can we get a higher density than the hex packing of circles? Dean Hickerson dean@math.ucdavis.edu