The CS Theory Stack Exchange is humming along nicely. It's a terrific, robust, and growing community that is clearly making an increasing contribution to the state of CS Theory research.
Something we keep thinking about, though, in the context of the entire Stack Exchange network, is how broad a Stack Exchange site should be. I blogged about this a little bit here:
So: the right size might be somewhere around the size of a university department. Somehow, the cultural anthropologists don’t mind sharing a building with the physical anthropologists, and when they both find themselves at the Yale-Harvard football game, you can bet that they’ll sit together and find something anthropological to talk about. Similarly, at Stack Overflow, the Java Entity Bean programmers at insurance companies don’t mind all the iPhone developers asking Objective C questions about the horrible, horrible game they’re working on. Heck, they might become iPhone developers one day. And they both share the humiliation of not being able to fix their uncle’s virus-infested Windows XP machine when they’re home for Thanksgiving.
So that leads to the obvious question... is this site too narrow? I don't know of many universities that have a Theoretical Computer Science department; they all have Computer Science departments and the algorithms purists don't seem to mind having Friday tea with the computer vision geeks. And the idea of meeting somebody who is working on AI is, it turns out, not entirely too horrible to contemplate.
I'm concerned that there are non-theoretical aspects of Computer Science research that don't have a home right now. If you look around Area51 you'll see proposals for crpytography, operating systems, compilers, cognitive science, numerical modeling, computer vision, bioinformatics, history of computers, and a lot of other fields that aren't quite reaching critical mass. We had an AI site that failed to ignite due to a lack of actual AI researchers.
I'm not saying all of those are on topic, but if a university had, say, two professors interested in cognitive science, I'm pretty sure they'd just stick them into the CS department and nobody would think that was strange or upsetting or crashing the party.
Right now, though, I see researchers all over the computer science department that don't really have a place to participate, and the idea of making dozens of thin little sites to cover every possible ACM SIG strikes me as ignoring one of the great reasons that Stack Overflow succeeded in the first place: because we brought together all programmers to talk about code, and we created a reliable and robust tagging system so that you could quickly find the topics and people that you cared about, and because nobody minded (and many people enjoyed) the occasional brushing-of-shoulders with people who shared the same values but worked in different technologies.
Can we do something here? I think that sticking to research-level conversation is a great common denominator, but there are an awful lot of interesting topics that are excluded right now which could really use a home. See, for example, arXiv's idea about what constitutes "computer science":
Artificial Intelligence; Computation and Language; Computational Complexity; Computational Engineering, Finance, and Science; Computational Geometry; Computer Science and Game Theory; Computer Vision and Pattern Recognition; Computers and Society; Cryptography and Security; Data Structures and Algorithms; Databases; Digital Libraries; Discrete Mathematics; Distributed, Parallel, and Cluster Computing; Emerging Technologies; Formal Languages and Automata Theory; General Literature; Graphics; Hardware Architecture; Human-Computer Interaction; Information Retrieval; Information Theory; Learning; Logic in Computer Science; Mathematical Software; Multiagent Systems; Multimedia; Networking and Internet Architecture; Neural and Evolutionary Computing; Numerical Analysis; Operating Systems; Other Computer Science; Performance; Programming Languages; Robotics; Social and Information Networks; Software Engineering; Sound; Symbolic Computation; Systems and Control
Some of that stuff is already on topic here, but a lot of it is sadly homeless in the Stack Exchange network.
My belief is that broadening this site to "computer science" and allowing discussion on any research-level topic that fits in one of the arXiv categories of Computer Science (and possibly even using those categories as tags) would make this site grow quickly into a much larger and stronger resource that attracts people in computer science departments around the world, rather than a thinner site that attempts to stitch together just the purely theoretical disciplines. Of course through the use of tags and our tag following feature, every participant could define their own filtered view of what kinds of topics they are interested in following, but if you want to reach outside of your narrow research interest once in a while there will be lots of other interesting stuff going on here too. And the opportunity to connect, even accidentally, with researchers who are ostensibly working outside of purely theoretical computer science but might, nonetheless, face the same types of problems seems like too good an opportunity to pass up.
What do you think?