See http://arxiv.org/abs/0704.2716 for the paper, titled "Constructing a quadrilateral inside another one". Be sure to look at version 3, which is much improved over the earlier versions. It's only 9 pages, and a pretty easy read, as math papers go. We are at work on a new version, which should improve the exposition and simplify the proof of the main theorem a bit, but I think the current version is actually publishable quality. We'll be submitting the new version to

*The Mathematical Gazette*.

This paper is an example of old-fashioned mathematics done with modern tools. There is nothing here that couldn't have been done in the 18th century, but without Geometer's Sketchpad I would never have come across the problem or have been able to obtain experimental evidence for our conjecture, now a theorem. And without Maple (or the reincarnation of Euler) we couldn't have done the calculations involved.

Technical production notes: Marshall wrote up the result using Scientific Workplace. Since I don't have a copy, I sent him my corrections as Word documents (using the MathType math editor), and produced wmf format graphics with Sketchpad. It would have really simplified our collaboration if we had the same software. What are other people using for collaborations?