Slides from my Graph Drawing talk, Delta-Confluent Drawings, are now online here.

I think the talk went well; at least, I got plenty of good questions and feedback about it. The last-minute decision to add a confluent H-tree drawing of $$K_{128}$$ (I had the rest of the slides ready a month ago) seems to have been a good one, since a lot of people seem to have been impressed by how such a dense graph could be made to look so uncluttered. Seok-Hee Hong asked about the possibility of three-dimensional confluent drawing; obviously, it wouldn't remove crossings, but it could be useful for reducing visual clutter, and I had a brief discussion with someone else about similar confluence-based decluttering of 2-dimensional drawings allowing crossings. Someone (I forget who, sorry) asked about combining clustered drawing with confluence; in fact, we'd been thinking about this after seeing a slide the previous day that appeared to be doing it. It seems like replacing the edges between clusters in a clustered drawing by a single confluent track, even if it loses information about exactly which edges are present, might be a useful visual simplification. David Wood repeated Janos Pach's question about whether confluent graphs are closed under complementation — delta-confluent graphs (aka distance-hereditary graphs) certainly aren't, and by the end of the day I'd heard from multiple sources that confluent graphs in general aren't either, though I still haven't seen the counterexample. But there's enough structure in distance-hereditary graphs that it may be possible to draw their complements confluently if not delta-confluently. Mike Goodrich showed me that our construction for confluent interval graph drawing also works for bipartite convex graphs, but he thinks their complements are not drawable. And Bettina Speckmann and Elena Mumford talked about the possibility of using confluence for flow maps in cartography. So I'm hopeful of seeing a lot more confluent drawing research in the near future.