# Re: What databases have taught me

Date: Sun, 25 Jun 2006 22:09:11 -0600

Message-ID: <MPG.1f090bd1fcc04b23989706_at_news.altopia.net>

Aloha Kakuikanu <aloha.kakuikanu_at_yahoo.com> wrote:

> However, his query was "find the dual of a graph" where the "dual" is

*> singular. Therefore, just accept the defeat.
*

Umm, alrighty then. Someone got up on the wrong side of the bed.

I was just providing information. That information is that finding the dual graph is trivial given some useful description of a plane embedding; and also that finding a plan embedding, while it is possible in linear time, is decidedly not a trivial problem. It's at least sufficiently non-trivial that even though I understand the general idea of Bob Tarjan's algorithm, I don't think I could actually do it in any language, SQL included, without a good bit of research. More research than I'd do just because of a newsgroup post. And I seem to know as much about the problem as most people here.

As it turns out, I don't much care whether SQL is a suitable language for finding a dual of a graph. I've never needed to find a dual of a graph. I just happened to have information that was being asked about.

I do find your word games interesting, though. I could easily conclude that the problem as originally stated is unsolvable (i.e., there is no "the" dual of a graph). However, it's going a bit far to start confusing graphs with their planar embeddings. Graphs still don't have faces, regardless of any mistakes that Dmitry may have made in phrasing the problem.

-- Chris Smith - Lead Software Developer / Technical Trainer MindIQ CorporationReceived on Mon Jun 26 2006 - 06:09:11 CEST