> > 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.
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 ;-) -- 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.
