This page is for my mathematical work, including publications and The La Jolla Combinatorics Repository, which contains online databases of covering designs, difference sets, signed difference sets, relative 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 stopped accepting covering design submissions to the website. After processing all the final submissions and correcting some issues, the database was frozen, and converted to json files. Those files, along with code to use them, are permanently available at zenodo.
My other databases are available in the same form at github and zenodo.
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.