I use G.line_graph().is_vertex_transitive() On Mon, Oct 29, 2012 at 7:12 AM, Jernej Azarija <azi.std...@gmail.com> wrote: > Hello! > > I am slowly implementing a patch that will provide some features for > symmetry testing of graphs. > > However I am already puzzled by the following attempt at testing for > edge-transitive graphs. Here is a straightforward textbook implementation > (the presented code omits the exceptional treatment of the singleton graph) > > === > def is_edge_transitive(self): > > A,T = self.automorphism_group(translation=True) > for (x,y,_) in self.edges(): > acts = set([]) > for g in A: > a,b = g(T[x]),g(T[y]) > acts.add((a,b) if a < b else (b,a)) > if len(acts) == self.size(): > return True > return False > === > > Testing the code (Petersen, Gray and path graph) it appears as if the > results are correct. But considering the following function computing the > number connected edge transitive graphs of given order > > === > def ecc(n): > c = 0 > for el in graphs.nauty_geng(str(n)+ " -c "): > if el.is_edge_transitive(): > c+=1 > return c > === > > we observe that > > sage: [ecc(i) for i in xrange(2,9)] > [1, 2, 3, 4, 6, 5, 8] > > which does not coincide with the data provided at oeis: > http://oeis.org/A095424/list . The difference gets even bigger if we count > all edge-transitive graphs instead of just connected. > > Anyone happens to see the flaw in the is_edge_transitive method? > > Best, > > Jernej > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To post to this group, send email to sage-devel@googlegroups.com. > To unsubscribe from this group, send email to > sage-devel+unsubscr...@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-devel?hl=en. > >
-- You received this message because you are subscribed to the Google Groups "sage-devel" group. To post to this group, send email to sage-devel@googlegroups.com. To unsubscribe from this group, send email to sage-devel+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
