On Monday, October 29, 2012 2:59:43 PM UTC+8, Georgi Guninski wrote: > > On Sun, Oct 28, 2012 at 07:17:59AM -0700, Nathann Cohen wrote: > > > > > > > Well, the documentation says > > > "Computes the girth of the graph. For directed graphs, computes the > > > girth of the undirected graph." > > > > > > So, that's what you are getting. :) > > > > > > > By the way, perhaps it is a bad idea to have this behaviour... What do > you > > think ?? > > > > Nathann > > > > I can't argue with the documentation :) > > Looks to me this is easy to fix if this is correct: > > For girth digraphs appear much easier than undirected graphs to me. > If M is the adjacency matrix of G, the girth is the smallest k > s.t. (M^k).trace != 0. 1 is a loop, 2 is a two cycle which appears > a valid girth for a digraph. > > If this is sane I can code it.
I wonder if it is less computationally demanding to walk around the graph than take powers of M, especially for large, but sparsely connected graphs. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
