On Wed, May 21, 2014 at 11:18 AM, kcrisman <kcris...@gmail.com> wrote: >> I'm about to give a very intro talk about graph theory in Sage, and >> the graph database section [1] of the reference manual begins: "... >> This class will also interface with the optional database package >> containing all unlabeled graphs with 8 or fewer nodes." >> >> I can't find any optional package to install to get these extra graphs >> up to 8 vertices. Anybody have any idea what happened to this? I >> realize that this stuff was originally done by Robert Miller and Emily >> Kirkman, who have moved on to other things (Home Depot and Actuarial >> work, I think...), but maybe somebody has kept track... If not, we >> should delete that line from the reference manual. >> >> There is a database included in Sage with graphs up to 7 nodes: >> >> for k in [1..9]: >> print k, GraphQuery(display_cols=['num_vertices'], >> num_vertices=k).number_of() >> >> 1 1 >> 2 2 >> 3 4 >> 4 11 >> 5 34 >> 6 15 >> 7 1044 >> 8 0 >> 9 0 >> >> So the builtin database is pretty tiny -- only just over a thousand >> graphs total? >> > > Well, the problem is that there is a LOT of information in the database, > some of which is quite expensive to compute for all isomorphism classes.
I appreciate that. > > Also, the database must still exist in some sense, or > http://artsci.drake.edu/grout/graphs/ wouldn't work... I just found all > three graphs with degree sequence 22222222 - which leads me to wonder how > that syntax would have to change if two-digit (in decimal) values for degree > were possible if the database were bigger ;-) That database http://artsci.drake.edu/grout/graphs/ was maybe a key part of Jason Grout's Ph.D. work -- and making a Sage version of it (which is what is in Sage up to 7 vertices) was one of the things that got him involved with Sage development. > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-devel+unsubscr...@googlegroups.com. > To post to this group, send email to sage-devel@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. -- William Stein Professor of Mathematics University of Washington http://wstein.org -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
