This page is for my mathematical work, including publications and The La Jolla Combinatorics Repository, which contains online databases of covering designs, difference sets, Steiner systems and circulant weighing matrices.

Alert!

I first put covering designs online in 1996. After 30 years, it’s time for this website (and eventually me) to be retired. As of March 1, 2026, I will stop accepting covering design submissions to the website. All the databases will be frozen, and the github and zenodo pages updated with the final versions of each one.

This website will stay up for some indeterminate amount of time, after which it will be replaced with this page. The data is being made available under a CC BY 4.0 license, meaning that anyone can use it however they see fit, as long as they give credit and make it clear what changes have been made.

It’s been a lot of work over the years to maintain these databases, and I’ve learned a lot more about HTML, MySQL, PHP, and AWS than I ever wanted to. But I’m grateful for all the feedback I’ve received, and the hundreds of researchers who have contributed tens of thousands of covering designs.