I believe there must be some error in the code that implements the Tutte polynomial of a graph in Sage. For example, the code
G = Graph(); G.allow_multiple_edges(True); #edges are (u,v,l), where (u,v) is the edge and l is the label, which determines edge order G.add_edges([(0,1,1),(1,5,2),(5,3,3),(5,2,4),(2,4,5),(0,2,6),(0,3,7),(0,4,8),(0,5,9)]); g = G.tutte_polynomial(); print g(1,1); print G.spanning_trees_count(); produces T(1,1): 60 Number of spanning trees: 52 But of course T_G(1,1) should be equal to the number of spanning trees. And I am tending to believe that the error is with the Tutte polynomial computation and not the second "spanning_trees_count()" method. -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/d/optout.
