Timeline for Smallest non-isomorphic strongly regular graphs
Current License: CC BY-SA 2.5
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 21, 2013 at 12:20 | comment | added | verret | The links appear to be broken. In the meantime, win.tue.nl/~aeb/graphs/srg/srgtab.html has some information. | |
| Sep 19, 2010 at 21:33 | comment | added | Emil | Peter Cameron discussed these graphs in a blog post recently: cameroncounts.wordpress.com/2010/08/26/the-shrikhande-graph | |
| Sep 19, 2010 at 20:57 | vote | accept | Hans-Peter Stricker | ||
| Sep 19, 2010 at 20:04 | comment | added | David Eppstein | Yes, e.g. in oai.cwi.nl/oai/asset/1817/1817A.pdf Brouwer and van Lint write that this is the only nonisomorphic pair with fewer than 25 vertices. | |
| Sep 19, 2010 at 19:40 | comment | added | Andrew D. King | Thanks for the clarification, David. Do you know if they are indeed the smallest, as they seem to be? | |
| Sep 19, 2010 at 19:13 | comment | added | David Eppstein | I forgot to add: they are obviously nonisomorphic because the neighborhood of a vertex in the Shrikhande graph is a 6-cycle, whereas the neighborhood in the line graph of $K_{4,4}$ is a pair of 3-cycles. | |
| Sep 19, 2010 at 19:10 | comment | added | David Eppstein | The two (16,6,2,2) graphs are the Shrikhande graph and the line graph of $K_{4,4}$. The Shrikhande graph may be obtained by forming a 5x5 grid of squares, adding a diagonal in the same direction to each square, and gluing opposite edges of the square grid to form a torus. | |
| Sep 19, 2010 at 18:23 | history | answered | Andrew D. King | CC BY-SA 2.5 |