I will argue against False. We've had the convention that Graph().is_connected() is True for the last n years. This was an arbitrary (if heedless) choice at the boundary of several definitions. It doesn't seem to be an undue source of bugs, so the only impact of changing this arbitrary choice to another arbitrary choice will be to subtly break backwards-compatibility and add warning noise.
I just consulted NetworkX, and I am convinced that their solution is the only reasonable change we could make: if len(G)==0: raise nx.NetworkXPointlessConcept( """Connectivity is undefined for the null graph.""") -- 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/groups/opt_out.