Thursday, November 12, 2009


This post is about surveys. It's motivated by one of my tasks last night, as I has to spend some time going over the final proofs for the survey Hash-Based Techniques for High-Speed Packet Processing, written with Adam Kirsch and George Varghese, which happily will finally be "officially" published (as part of a DIMACS book). The link is to a submitted version; I'll try to find a "final" version to be put up when possible, but the delta is small. I'll take the liberty of complimenting my co-authors on the writing; if you want a quick guide on the connection between hashing and routers, it should be a good starting point.

It occurs to me that I've written a number of surveys -- I mean, a lot*. Indeed, I'm sure in some circles I'm known mostly (and, perhaps, possibly only) for some survey I've written. That is not meant as self-promotion; indeed, I'm well aware that some people would view this as quite a negative. After all, as comments in a recent post felt it important to point out (and argue over), the mathematician Hardy wrote: Exposition, criticism, appreciation, is work for second-rate minds. I would disagree, and I would hope to encourage others to write surveys as well.

I've found writing surveys a useful tool in both doing and promoting my research. I've done surveys for multiple reasons. It's a good way to learn a new topic. It's a good way to bring some closure to a long line of work for oneself. It's a good way to frame and popularize a research direction or a set of open problems. And finally, I've found it's a good way to provide a bridge between the theoretical and practical communities.

Earlier in my career, there didn't seem to be much of a home for publishing surveys. I was fortunate that the journal Internet Mathematics started when it did, and was willing to take surveys. Otherwise, I'm not sure where my surveys on Bloom filter and power laws -- my two most cited (and I would guess read) would have ended up. These days, surveys seem to have become more acceptable, thankfully. The Foundations and Trends series, in particular, have provided a natural outlet that has spurred a number of impressive and useful surveys. I admit these booklets tend to be a bit longer than what I have usually aimed for, but I was usually hoping just to find some journal (or conference) that would take a survey, so length was actually a negative. I imagine someday I'll get up the energy to write something for this series.

But perhaps there are now other mechanisms for producing and publishing surveys. I view Dick Lipton's blog as providing one or more well-written mini-surveys every week (a truly amazing feat). Wikipedia provides a means for what seem to be essentially collaborative mini-surveys to also be written on technical topics; perhaps some Wiki-based tool or archive could be developed that would allow for richer, growing and changing surveys with multiple contributing authors.

In any case, when somebody suggests to you that exposition is for a second-rate mind, keep in mind that not everybody agrees. Writing a survey has become downright respectable. If you feel like disagreeing strongly, in the most vocal way possible, then please, go ahead and write a survey as well.

* Here's a possibly complete list. Co-author information and other related information can be found on my List-of-Papers page. Current links are provided here for convenience.

Some Open Questions Related to Cuckoo Hashing
Hash-Based Techniques for High-Speed Packet Processing.
A Survey of Results for Deletion Channels and Related Synchronization Channels
Human-Guided Search
Toward a Theory of Networked Computation
Network Applications of Bloom Filters: A Survey
Digital Fountains: A Survey and Look Forward
A Brief History of Generative Models for Power Law and Lognormal Distributions
The Power of Two Random Choices: A Survey of Techniques and Results


David Molnar said...

Gian-Carlo Rota pointed out that, as a mathematician, you will be remembered primarily for your expository work. So if you care about being remembered, that's reason enough to do a good survey.

Anonymous said...

Hardy wrote: Exposition, criticism, appreciation, is work for second-rate minds. I would disagree, and I would hope to encourage others to write surveys as well.

Forgetting for the moment US-academia
style hyperbole (as exemplified by recommendation letters that we all read and write) -- lets remember in Hardy's book the first rate minds he had the opportunity to collaborate were those of Littlewood and Ramanujan. At the time he wrote these lines he did not consider himself to be first-rate either. So being second-rate by Hardy's criteria is pretty darn good. Not many (if any) TCS researchers will actually fall in that category. So no need to worry on this account -- write as many surveys as you want (I do think it is a very useful contribution to the community).

Unknown said...

Surveys are wonderful. I've cited yours on power laws; it was quite useful as an academic counterpoint to some of the more "popular math" ones. And of course there's part of me that can't wait for the next survey on my topic of interest, since that's an automatic cite of my papers on the subject right there.

But I understand why some people turn their noses up at them. Little (or none) of the content is original work, and, even though we spend far more time on other tasks than we do on the nuts and bolts of research, it's the "original contribution" which gets the glamor. It's the goal of the Ph.D. itself, and original work is romanticized in general culture; in Rent, the lead character's goal is to write "one great song," not perform it well or even succeed.

And I'm sure there are people who see surveys as a "cheat"; not only do you have to do not research, but you get cited more than "substantive" papers! How dare you! Nevertheless, they're some of the most important papers in the world. I wonder how many man-years of redundancy has (or could have) been avoided thanks to a well-timed survey paper.

Anonymous said...

Thanks for the links and writing the surveys.

Didnt Hamming in his famous lecture comment that for established researchers, a book is a bigger contribution than papers. I guess one could extend the comment for surveys.

Geoff Knauth said...

A survey will interest the casual reader, who will explain it to a child, who will end up pursuing the topic as a first rate mind.