Dan Gordon’s Home Page

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.


For some time I have wanted to make a permanent repository for these datasets, so that if something
happens to this webpage they will always be available, and to provide a permanent DOI for citing the

I did this for
DOIsigned difference sets in 2023, and have now done the same for DOIdifference sets, DOIcirculant weighing matrices, and DOIcovering designs.

Each of these consists of the data as one or more json files, some minimal python code to search the files and pull out objects from them, and a Jupyter notebook to provide a graphical interface.

The only one of these databases that changes regularly is covering designs. The data will be updated periodically (at most a few times per year), so this webpage will remain the place to get the most up-to-date information.