I wanted a listing of the blocks of the 2 nonisomorphic STS (Steiner Triple System) on 13 points and the 80 nonisomorphic STS on 15 points. Over at designtheory.org there is a database of t-designs. An STS(13) corresponds to a t-design t=2, v=13, b=26, r=6, k=3, L=1 and an STS(15) corresponds to a t-design t=2, v=15, b=35, r=7, k=3, L1. Here is some code that uses pydesign to read the blocks from DTRS external representation files:
Here’s the source: STS_13_15.py.
Date: 2009-05-11 18:10:46 UTC
Author: david joyner
Why don’t you add this to Sage? Sage’s incidence structure class is based on pydesign but the database read-write functionality was left out. Please feel free to add it back in and ask me or Dan Gordon to referee.