Over the next week, I'll present some thoughts related to the STOC PC meeting, which wrapped up earlier today. (Please don't send mail to ask about your paper(s). Messages will be sent out sometime next week.)
Today's post will be about basic logistics, which you wouldn't normally think about, unless you suddenly found yourself running the meeting. We started with roughly 150-160 papers left to consider. At 5 minutes on average per paper, you're already at about 13 hours. And if you slip to 6 minutes on average per paper, well, now you're at 15 to 16 hours, which when you consider overhead time (computer setup, lunch, the occasional rest break), you see the difference between that 5 and 6 sharply when you know people have flights to catch at the end of day 2. I think the hardest part of the meeting, from my end, was simply time management.
We started at 9 am on day 1, with plans to break at 6. It became clear that we were falling behind schedule, so we changed the dinner reservation and kept going until 7. We still seemed behind -- and with most of the easier accept and reject decisions behind us -- so we agreed to meet at 8:30 am on day 2. The mumblings and rumblings over dinner of "We're never going to finish on time" were worrisome, and I stayed up late looking over and organizing the remaining papers, so we could go through a bunch very quickly on day 2. I was definitely aided in this goal by the rest of the committee, who had clearly also done additional prepping post-dinner and were ready when they came in the door. In the first hour we made up our deficit in the schedule, and finished our decisions around 2:30, actually leaving us a comfortable amount of time to talk about other organizing issues before people started heading to the airport for their flights around 3.
While it all ended up OK, perhaps I could have done better day 1.
Also, the lesson for future PC members -- be ready to talk when your papers come up, and be prepared to make your points quickly. The seconds add up! I thank the committee for both putting in the extra long hours and for being well prepared, so we could finish on time. And everyone who submitted papers should be thanking them as well.
Another piece of "chair advice" I was told that I can't over-emphasize enough -- have someone whose job it is take notes and record the status of papers as you go. During the meeting I vaguely asked one of the PC members to keep track of things. At the end of the first night, trying to prepare for day 2, I would have been lost without his guide as to where everything stood. As chair (particularly as a single chair -- we should have co-chairs...) I found it difficult to keep things running, enter things into the system, and track things so I could go back and really see where everything was; the notetaker essentially did the tracking job for me, making the whole meeting run much more smoothly, and allowing me to get some sleep before the second day.
And speaking of sleep, I'm very tired, and need at least a day without thinking of anything related to STOC.
Friday, January 30, 2009
Wednesday, January 28, 2009
Graduate Student Folders Part II
We're getting to the point where we have to make our decisions on graduate student admissions. In the theory group at Harvard we got a sizable number of folders that we've cut down to about 25. We'll probably cutting those down to about 10 acceptances.
There's clearly an abundance of good people, who could become solid TCS researchers. And as we went over in my last post on this, it's difficult to choose based on an application who will become successful.
My guilt in having to choose from among these many talented people is assuaged mostly by my concern for the people who we do admit to graduate school, especially in TCS. Where will the jobs be when these people graduate? I've heard the arguments that CS is still expanding, well maybe not in America but elsewhere in the world, and that PhDs can find other work besides being a professor. I've seen that most of the other students I knew as a graduate student in Berkeley have ended up with good positions -- mostly professors -- albeit some after a number of years of postdocs. But still, at the end of the day, when I do the math, it just doesn't add up. I expect to be in my position for at least 30 years (barring the current curse of Harvard CS faculty to be moved into administration); how many professors (or scientists at research labs) can I produce over my lifetime?
The financial meltdown has only raised my concerns that in CS generally (and theory in particular) we've been living through a bubble, and we'll all be shocked when that bubble pops, though we shouldn't be.
I'm not so entirely pessimistic -- CS PhDs, for as far as I can see, should have no trouble getting pretty good jobs. But how many will get the jobs they think they're getting the PhD for? (Note the internal mental bias here -- professors remember mostly the students who did go on to get faculty/research jobs...) We'll see.
There's clearly an abundance of good people, who could become solid TCS researchers. And as we went over in my last post on this, it's difficult to choose based on an application who will become successful.
My guilt in having to choose from among these many talented people is assuaged mostly by my concern for the people who we do admit to graduate school, especially in TCS. Where will the jobs be when these people graduate? I've heard the arguments that CS is still expanding, well maybe not in America but elsewhere in the world, and that PhDs can find other work besides being a professor. I've seen that most of the other students I knew as a graduate student in Berkeley have ended up with good positions -- mostly professors -- albeit some after a number of years of postdocs. But still, at the end of the day, when I do the math, it just doesn't add up. I expect to be in my position for at least 30 years (barring the current curse of Harvard CS faculty to be moved into administration); how many professors (or scientists at research labs) can I produce over my lifetime?
The financial meltdown has only raised my concerns that in CS generally (and theory in particular) we've been living through a bubble, and we'll all be shocked when that bubble pops, though we shouldn't be.
I'm not so entirely pessimistic -- CS PhDs, for as far as I can see, should have no trouble getting pretty good jobs. But how many will get the jobs they think they're getting the PhD for? (Note the internal mental bias here -- professors remember mostly the students who did go on to get faculty/research jobs...) We'll see.
Tuesday, January 27, 2009
SIGCOMM PC starting... STOC PC ending...
I guess there's another week until the "official deadline" for SIGCOMM, but the deadline for registration of abstracts/titles has already happened, and I was asked to "bid" on papers I was interested in. It's hard to tell from the limited information, but it seems like there are plenty of interesting papers. Mostly I was looking for papers covering algorithmic engineering or just plain algorithmic problems, the econ/CS interface, and coding (network coding seems to be getting bigger), but there were certainly papers outside those areas that caught my eye. Out of the 300-400 submissions, there were more than 50 that looked interesting enough for me to request them; I was only asked to choose at least 30 to start.
Of course, since the whole process is double-blind, I don't know who submitted the papers, and hopefully the authors won't be able to figure out which reviews I end up writing.
This would all be great fun, but there's of course STOC to finish up. We've rejected about half the papers so far (we're still in the pre-meeting stage). Of course, that's the "easy" part. Now things get harder.
Of course, since the whole process is double-blind, I don't know who submitted the papers, and hopefully the authors won't be able to figure out which reviews I end up writing.
This would all be great fun, but there's of course STOC to finish up. We've rejected about half the papers so far (we're still in the pre-meeting stage). Of course, that's the "easy" part. Now things get harder.
Sunday, January 25, 2009
More on Algorithms and Implementation
In the comments on my last post on algorithms and implementation, someone asked where to publish when you sit in the middle, and how can a graduate student succeed by being in the middle. The comments seemed to suggest that publishing was hard and succeeding as a graduate student this way was largely impossible.
Sadly, and disconcertingly, I find myself largely agreeing. I think the theory community has developed to the point where, almost universally, if you want to earn a reputation as a top theorist in graduate school, you have to publish FOCS/STOC/SODA papers. And really this can't be done by focusing on practical issues. More practical papers can be published in other venues -- WWW, INFOCOM, even SPAA and PODC -- but to the theory community these papers don't carry as much weight. (Note: yes, obviously there are RARE exceptions.)
Strangely, I still think there's a reasonable job market for practically-minded theorists, both in research labs, and in smaller universities, where they'd much prefer a theorist who would interact with other groups (like networking or AI) because they really aren't big enough to have theorists who don't have "outside interests". And I think evidence of being able to work with practitioners helps most any theorist looking for a job -- you just can't build your reputation on it. But it can be hard to get that balance of theory and practice "right" as a graduate student.
I see a fair amount of people who are theoretical but practically minded simply going into other fields, either as a graduate student or after. You can be a "theoretical" networking person or AI person and succeed, and a number of graduate students who could be theorists figure out they'll be better off in these areas. You can start out as a FOCS/STOC/SODA person and then branch out to other areas. Go look at Karger or Kleinberg's DBLP pages and see how much more they've been doing in the recent past outside the confines of FOCS/STOC/SODA compared to earlier in their careers. (Or look at John Byers and Soumen Chakrabarti, who worked primarily in theory as graduate students, but switched to other areas.)
Perhaps this would make a good conference panel someday. (Offhand I'd recommend getting Mikkel Thorup and Muthu Muthukrishnan to participate -- they seem to me like role models for people who want to sit in the middle -- though I can think of many others as well...) Heck, come to think of it, I'm the STOC chair, maybe it would make a good panel coming up real soon. Please let me know if you'd like a panel on this issue -- something like "How to Succeed doing Practical Theory?" -- at STOC.
Sadly, and disconcertingly, I find myself largely agreeing. I think the theory community has developed to the point where, almost universally, if you want to earn a reputation as a top theorist in graduate school, you have to publish FOCS/STOC/SODA papers. And really this can't be done by focusing on practical issues. More practical papers can be published in other venues -- WWW, INFOCOM, even SPAA and PODC -- but to the theory community these papers don't carry as much weight. (Note: yes, obviously there are RARE exceptions.)
Strangely, I still think there's a reasonable job market for practically-minded theorists, both in research labs, and in smaller universities, where they'd much prefer a theorist who would interact with other groups (like networking or AI) because they really aren't big enough to have theorists who don't have "outside interests". And I think evidence of being able to work with practitioners helps most any theorist looking for a job -- you just can't build your reputation on it. But it can be hard to get that balance of theory and practice "right" as a graduate student.
I see a fair amount of people who are theoretical but practically minded simply going into other fields, either as a graduate student or after. You can be a "theoretical" networking person or AI person and succeed, and a number of graduate students who could be theorists figure out they'll be better off in these areas. You can start out as a FOCS/STOC/SODA person and then branch out to other areas. Go look at Karger or Kleinberg's DBLP pages and see how much more they've been doing in the recent past outside the confines of FOCS/STOC/SODA compared to earlier in their careers. (Or look at John Byers and Soumen Chakrabarti, who worked primarily in theory as graduate students, but switched to other areas.)
Perhaps this would make a good conference panel someday. (Offhand I'd recommend getting Mikkel Thorup and Muthu Muthukrishnan to participate -- they seem to me like role models for people who want to sit in the middle -- though I can think of many others as well...) Heck, come to think of it, I'm the STOC chair, maybe it would make a good panel coming up real soon. Please let me know if you'd like a panel on this issue -- something like "How to Succeed doing Practical Theory?" -- at STOC.
Friday, January 23, 2009
Algorithms and Implementation
I was leafing (again) through George Varghese's text, Network Algorithmics
, and this caught my eye:
In summary, the uncritical use of standard algorithms can miss implementation breakthroughs because of inappropriate measures (e.g., for packets filters such as BPF, the insertion of a new classifier can afford to take more time than search), inappropriate models (e.g., ignoring the effects of cache lines in software or parallelism in hardware), and inappropriate analysis (e.g., order-of-complexity results that hide constant factors crucial in ensuring wire speed forwarding).These words succinctly express feelings I commonly have. Standard algorithms theory often fails to live up to its promise in practice, untethered as it has become from applications. At the same time, a properly designed algorithm can yield immense breakthroughs in performance, so implementors cannot do without them. I believe we need more people willing to sit in the middle, but perhaps first we need more creative ways to bring theory and practice, or theorists and practitioners, together.
Thus another purpose of this book is to persuade implementors that insight into algorithms and the use of fundamental algorithmic techniques such as divide-and-conquer and randomization is important to master.
Thursday, January 22, 2009
Georgia Tech visit
I had the pleasure of visiting Georgia Tech Wednesday, giving a theory seminar, in this case my survey talk on Deletion Channels.
A fun day filled with conversations about research, kids, and other goings-on. Highlights include getting to catch up with my academic older sister Dana Randall and younger brother Eric Vigoda. And this trip, as it seems with every trip I've taken to Georgia Tech, my host Vijay Vazirani exceeded expectations with his choice of dinner location. (And by now, I have high expectations for meals in Atlanta!)
The department has really grown into a theory powerhouse (and has a very strong networking group as well). For some time it's been on my list of schools undergraduates should think about for graduate school (but might not have realized they should be thinking about). The visit was a strong reminder of why.
A fun day filled with conversations about research, kids, and other goings-on. Highlights include getting to catch up with my academic older sister Dana Randall and younger brother Eric Vigoda. And this trip, as it seems with every trip I've taken to Georgia Tech, my host Vijay Vazirani exceeded expectations with his choice of dinner location. (And by now, I have high expectations for meals in Atlanta!)
The department has really grown into a theory powerhouse (and has a very strong networking group as well). For some time it's been on my list of schools undergraduates should think about for graduate school (but might not have realized they should be thinking about). The visit was a strong reminder of why.
Saturday, January 17, 2009
Summer Funding
I should have blogged about this before, but didn't notice over break that Yale had "agreed to pay7.6 million to resolve allegations" regarding how it was handling research grants. My understanding is that this primarily related to summer funding -- the government apparently objects to professors saying they're working 100% on their research over the summer and then doing other stuff. (You know, pesky things like writing letters of recommendation or preparing for next semester's classes.) Anyone with more info, please speak up or link in the comments.
Now, of course, this all just boils down to accounting. The university (nominally) pays 9 months of salary, but strangely, we seem to be expected to also be working on our government-funded research during the academic year as well. One would think there might be some understanding that there's some appropriate blurring of time spent on various tasks. But Harvard, responsive as always when it sees another school getting fined, is changing its process to avoid the same sort of investigation. I don't quite get how this works, but apparently my June summer funding for '09 will be paid out over the spring semester, and the rest of my summer funding will be paid out over the fall semester. I'm assuming that when I eventually have to fill out forms accounting for my time they'll be modified so that research time during the year is counted some way as well.
As one colleague said to me, the new system is stupid, but so was the old system, and sometime down the road, some bureaucrat will decide this is wrong, and we'll switch to a different stupid system. What I find most odd about the new system is it seems at least part of the time I'm getting paid from a government grant for work I will only do in the future. That's OK with the government? I imagine if for whatever reason I later decided not to work over June, they'd pull the money back out of future paychecks. I also suppose this provides some understanding of why grant overhead rates, which I generally complain about, are so ridiculously high; if there's really this much paperwork (and computer accounting software setup) involved in grant management, maybe the overhead really is necessary.
Now, of course, this all just boils down to accounting. The university (nominally) pays 9 months of salary, but strangely, we seem to be expected to also be working on our government-funded research during the academic year as well. One would think there might be some understanding that there's some appropriate blurring of time spent on various tasks. But Harvard, responsive as always when it sees another school getting fined, is changing its process to avoid the same sort of investigation. I don't quite get how this works, but apparently my June summer funding for '09 will be paid out over the spring semester, and the rest of my summer funding will be paid out over the fall semester. I'm assuming that when I eventually have to fill out forms accounting for my time they'll be modified so that research time during the year is counted some way as well.
As one colleague said to me, the new system is stupid, but so was the old system, and sometime down the road, some bureaucrat will decide this is wrong, and we'll switch to a different stupid system. What I find most odd about the new system is it seems at least part of the time I'm getting paid from a government grant for work I will only do in the future. That's OK with the government? I imagine if for whatever reason I later decided not to work over June, they'd pull the money back out of future paychecks. I also suppose this provides some understanding of why grant overhead rates, which I generally complain about, are so ridiculously high; if there's really this much paperwork (and computer accounting software setup) involved in grant management, maybe the overhead really is necessary.
Wednesday, January 14, 2009
Graduate Student Folders
When I'm not looking over STOC papers the next few weeks, I'll also be looking over graduate student admissions folders. (At Harvard, we're small enough that the theory folks just split up all the folders and then meet to discuss them.) Even though I've been doing this for a while, I'd love to hear from all of you -- what should I -- or we as a community -- be looking for in selecting graduate students?
I think that on the theory side we tend to look for pure brainpower over other skills. Arguably moreso in theory than in other subjects, raw intelligence matters most. (I'm not saying I agree with that argument; I'm just saying it's an argument.) I think we also know that grades don't necessarily provide the right information we need to judge this, however, and so we look for evidence that one has the ability to do research in the form of actual research projects accomplished or letters from faculty members we know (and believe) who suggest that there's intellectual power and creativity there.
I do think most faculty do keep in mind the other skills that can make for a successful student. Communication skills, the ability to work well with others, a sense of what they want to accomplish, the mindset to deal with the one-step-forward-two-steps-back nature of research -- all of these also come into play in decision-making. These can be much harder to judge, however, unless they're clearly marked by their absence in some way.
I wonder if the competitive landscape for graduate slots at the top schools causes us to miss out on some promising people. Over at the FemaleScienceProfessor blog, she discusses why she'd rather take the motivated B student over a lot of A students for undergraduate research projects. I'm curious, having no evidence one way or another, do people think we're doing a good job getting B undergraduates who could become great researchers into the pipeline early on enough so they can construct a good application for graduate school? Do we accept enough of these students when they apply?
I think that on the theory side we tend to look for pure brainpower over other skills. Arguably moreso in theory than in other subjects, raw intelligence matters most. (I'm not saying I agree with that argument; I'm just saying it's an argument.) I think we also know that grades don't necessarily provide the right information we need to judge this, however, and so we look for evidence that one has the ability to do research in the form of actual research projects accomplished or letters from faculty members we know (and believe) who suggest that there's intellectual power and creativity there.
I do think most faculty do keep in mind the other skills that can make for a successful student. Communication skills, the ability to work well with others, a sense of what they want to accomplish, the mindset to deal with the one-step-forward-two-steps-back nature of research -- all of these also come into play in decision-making. These can be much harder to judge, however, unless they're clearly marked by their absence in some way.
I wonder if the competitive landscape for graduate slots at the top schools causes us to miss out on some promising people. Over at the FemaleScienceProfessor blog, she discusses why she'd rather take the motivated B student over a lot of A students for undergraduate research projects. I'm curious, having no evidence one way or another, do people think we're doing a good job getting B undergraduates who could become great researchers into the pipeline early on enough so they can construct a good application for graduate school? Do we accept enough of these students when they apply?
Monday, January 12, 2009
Deletion Channel Paper
There's a new paper with bounds on the capacity of the deletion channel on the arxiv by Fertonani and Duman. The main results are some new upper bounds which generally are better than the upper bounds found in a paper by Diggavi, Mitzenmacher, and Pfister, which was the first look at the problem in a long while.
The bounds achieved are very nice. They use a simpler approach than our earlier paper, essentially dividing the input or output into fixed sized blocks and numerically calculating the capacity per block. With clever manipulation, they can extend the bounds in various ways -- the nicest result (in my mind) being that, in the limit as the deletion probability d goes to 1, the capacity is upper bounded by 0.49(1-d). [Our previous result gave a bound of 0.79(1-d), and some of my work on lower bounds showed that the capacity is at least 0.11(1-d).]
It seems to me their work raises some interesting questions. One question is the following: at some point, they have to rely on numerical calculations to determine their upper bounds, using the Blahut-Arimoto algorithm to calculate the capacity of a fixed finite channel. Their approach is limited by this calculation; for instance, if one "chops" the input into blocks of 10 bits, then there are 1024 possible input sequences and 2048 possible output sequences for the deletion channel, and essentially they have to compute the capacity of this fixed channel in a "brute force" way, which requires keeping track of the probability that each input results in each output. Bigger blocks means better bounds but bigger calculations. (Technically one can find ways to avoid keeping the entire 1024 by 2048 probability matrix, since it's fairly sparse, but the calculations still grow big very fast.)
Is there any hope for an approximate version of the Blahut-Arimoto algorithm that would give provable upper bounds on the capacity but could take smaller time/space? It would seem there might be other uses for an approximate expectation-maximization procedure, although perhaps generally one wants such good approximations that there's no real benefit in practice. Any thoughts?
The bounds achieved are very nice. They use a simpler approach than our earlier paper, essentially dividing the input or output into fixed sized blocks and numerically calculating the capacity per block. With clever manipulation, they can extend the bounds in various ways -- the nicest result (in my mind) being that, in the limit as the deletion probability d goes to 1, the capacity is upper bounded by 0.49(1-d). [Our previous result gave a bound of 0.79(1-d), and some of my work on lower bounds showed that the capacity is at least 0.11(1-d).]
It seems to me their work raises some interesting questions. One question is the following: at some point, they have to rely on numerical calculations to determine their upper bounds, using the Blahut-Arimoto algorithm to calculate the capacity of a fixed finite channel. Their approach is limited by this calculation; for instance, if one "chops" the input into blocks of 10 bits, then there are 1024 possible input sequences and 2048 possible output sequences for the deletion channel, and essentially they have to compute the capacity of this fixed channel in a "brute force" way, which requires keeping track of the probability that each input results in each output. Bigger blocks means better bounds but bigger calculations. (Technically one can find ways to avoid keeping the entire 1024 by 2048 probability matrix, since it's fairly sparse, but the calculations still grow big very fast.)
Is there any hope for an approximate version of the Blahut-Arimoto algorithm that would give provable upper bounds on the capacity but could take smaller time/space? It would seem there might be other uses for an approximate expectation-maximization procedure, although perhaps generally one wants such good approximations that there's no real benefit in practice. Any thoughts?
Sunday, January 11, 2009
Co-Chairs
Although it's far from over, I'm already clear that one of my recommendations for the future of FOCS/STOC conferences is to start having co-chairs instead of a single chair.
The reasons for having co-chairs that I can see include:
1) Chairing involves a lot of administrative work, often bursts for short intervals. Being able to share that kind of work seems to have a huge upside.
2) Although I don't think it's come up for STOC yet, having a co-chair watch your back can help avoid silly mistakes.
3) Particularly for FOCS/STOC, having co-chairs from two different subareas (one from a more algorithmic side and one from the complexity side) would seem to offer better coverage.
Many conferences in other areas of comparable size to FOCS/STOC have co-chairs (e.g., NSDI, SIGCOMM that I know of) and in my experience as a PC member it's always gone well.
What are the possible downsides of co-chairs?
1) Whenever two people are co-in-charge, they have to work together well. I hope it wouldn't be too hard to find people who could capably co-chair for these conferences.
2) I imagine it can be hard finding people willing to chair; now you'd have to find 2! Although I actually think it might make it easier to get people to accept if they can co-chair -- it will seem like less work, and if one person is more experienced, you could have a somewhat less experienced person co-chair.
The reasons for having co-chairs that I can see include:
1) Chairing involves a lot of administrative work, often bursts for short intervals. Being able to share that kind of work seems to have a huge upside.
2) Although I don't think it's come up for STOC yet, having a co-chair watch your back can help avoid silly mistakes.
3) Particularly for FOCS/STOC, having co-chairs from two different subareas (one from a more algorithmic side and one from the complexity side) would seem to offer better coverage.
Many conferences in other areas of comparable size to FOCS/STOC have co-chairs (e.g., NSDI, SIGCOMM that I know of) and in my experience as a PC member it's always gone well.
What are the possible downsides of co-chairs?
1) Whenever two people are co-in-charge, they have to work together well. I hope it wouldn't be too hard to find people who could capably co-chair for these conferences.
2) I imagine it can be hard finding people willing to chair; now you'd have to find 2! Although I actually think it might make it easier to get people to accept if they can co-chair -- it will seem like less work, and if one person is more experienced, you could have a somewhat less experienced person co-chair.
Thursday, January 08, 2009
So, how's STOC going?
I suggested that I'd blog about my experiences as STOC PC chair, so I thought I'd give an update.
We're nearing the point where all the "first round" reviews are supposed to be in. All papers had 3 PC members assigned to them, and my goal was to have 3 reviews for each paper a few weeks before the PC meeting. So far, it seems to be going well; most PC members have been putting in reviews. A few who seem to be working with an offline scorecard haven't uploaded what they've completed -- which makes things a bit more difficult for me, naturally :( -- and I expect some papers won't have 3 reviews by the deadline for various reasons, the most likely being that a subreviewer hasn't finished. Subreviewers, please get things in! (And thank you.)
After that point, I hope to reject a slew of papers outright. Recall that I'm trying a new scoring scale. 1 = bottom 50%, 5 = top 10 %, other scores in between. Anything with 3 1's seems to be an easy reject. Arguably, if there's no score of 3 or above in the 3 reviews, a paper should be rejected. To be clear I won't make those decisions unilaterally, but will set up votes for the PC.
The other work at this point is finding more reviewers for papers with widely disparate scores (where the problem does not seem to be "this paper has a bug" that one reviewer noticed but others didn't, but rather a wide disagreement on the quality/importance of the result) or for papers that seem like they'll be on the borderline. Here I'm looking for people both on and off the PC -- so don't be too surprised if you get an e-mail asking for a quick review -- with the emphasis on trying to find relevant experts in the area of the paper.
How many papers will have both a 1 and a 5 score? (Or 2/5s, or 1/4s?) Seems like a statistic for the business meeting roundup. But so far, the answer seems to be more than you might think...
We're nearing the point where all the "first round" reviews are supposed to be in. All papers had 3 PC members assigned to them, and my goal was to have 3 reviews for each paper a few weeks before the PC meeting. So far, it seems to be going well; most PC members have been putting in reviews. A few who seem to be working with an offline scorecard haven't uploaded what they've completed -- which makes things a bit more difficult for me, naturally :( -- and I expect some papers won't have 3 reviews by the deadline for various reasons, the most likely being that a subreviewer hasn't finished. Subreviewers, please get things in! (And thank you.)
After that point, I hope to reject a slew of papers outright. Recall that I'm trying a new scoring scale. 1 = bottom 50%, 5 = top 10 %, other scores in between. Anything with 3 1's seems to be an easy reject. Arguably, if there's no score of 3 or above in the 3 reviews, a paper should be rejected. To be clear I won't make those decisions unilaterally, but will set up votes for the PC.
The other work at this point is finding more reviewers for papers with widely disparate scores (where the problem does not seem to be "this paper has a bug" that one reviewer noticed but others didn't, but rather a wide disagreement on the quality/importance of the result) or for papers that seem like they'll be on the borderline. Here I'm looking for people both on and off the PC -- so don't be too surprised if you get an e-mail asking for a quick review -- with the emphasis on trying to find relevant experts in the area of the paper.
How many papers will have both a 1 and a 5 score? (Or 2/5s, or 1/4s?) Seems like a statistic for the business meeting roundup. But so far, the answer seems to be more than you might think...
Tuesday, January 06, 2009
Preparing for Class
It's that time of the year where it's time to get my next class ready. I could use your help.
For various odd reasons, in the coming semester I'll be teaching both my undergraduate Algorithms (and Data Structures) class [it's not parenthesized like that in the course catalog, but it probably should be], and my graduate "big data" class, dubbed Algorithms at the End of the Wire. For the graduate class, I cover a variety of topics -- last time, the main areas were search engine algorithms, compression, stream-based algorithms and data structures, and coding (network coding and otherwise), and essentially each class the students are supposed to come in having read a couple of papers. One of the goals of the class is to present algorithmic theory and practice, so I emphasize trying to find practical papers that really make use of underlying theory, or theory papers that really try to impact how a practical problem is thought about. Another goal of the class is to introduce students to the ways of research, by having them read both ancient classics (like, say, Kleinberg's HITS paper) and more recent (e.g. the last year or two) papers.
I'd be interested in any suggestions for good papers for students to read -- particularly recent papers. Don't feel tied to the topics above -- I should be trying to keep up with good papers bridging the algorithm/theory divide in all areas!
For various odd reasons, in the coming semester I'll be teaching both my undergraduate Algorithms (and Data Structures) class [it's not parenthesized like that in the course catalog, but it probably should be], and my graduate "big data" class, dubbed Algorithms at the End of the Wire. For the graduate class, I cover a variety of topics -- last time, the main areas were search engine algorithms, compression, stream-based algorithms and data structures, and coding (network coding and otherwise), and essentially each class the students are supposed to come in having read a couple of papers. One of the goals of the class is to present algorithmic theory and practice, so I emphasize trying to find practical papers that really make use of underlying theory, or theory papers that really try to impact how a practical problem is thought about. Another goal of the class is to introduce students to the ways of research, by having them read both ancient classics (like, say, Kleinberg's HITS paper) and more recent (e.g. the last year or two) papers.
I'd be interested in any suggestions for good papers for students to read -- particularly recent papers. Don't feel tied to the topics above -- I should be trying to keep up with good papers bridging the algorithm/theory divide in all areas!
Friday, January 02, 2009
Consistency in Scoring
Having just finished serving on the NSDI PC committee, and being hard at work on the STOC committee, one issue that has been on my mind is consistency in scoring papers. Ideally, when submitting to a conference, it shouldn't matter WHO reads your paper; your score should be intrinsic to your work. Of course, we don't expect -- or even necessarily want -- the complete ideal; there will be differences of opinion that occur for natural reasons. Arguably, for example, "visionary" papers are hard to judge and tend to lead to differences of opinion. So you can take solace that if you get widely varying reviews and your paper is rejected, your paper was probably just too visionary. The more cynical among us might instead think that large variances in opinion have to do with how close the reviewer is to the subfield of the paper. In theory, my take is that referees within a subarea generally give higher marks to papers in that subarea. (At NSDI, I found myself with a different impression; if anything, I thought referees working in a subarea tended to be a bit harsher towards papers in that subarea!)
My impression historically has been that there's more variance on the theory side of the world than on the systems side, particularly for the big conferences like FOCS/STOC/SODA. I was amazed, on the whole, at the consistency of NSDI reviews for papers I was on. STOC reviews are coming in, and I'm looking forward to seeing how consistent things are there, but my early impression is that there's not the same consistency, and it's interesting to hypothesize why. [Perhaps, after it's all over, I'll attempt to gather some real quantitative data on the issue, to see if my impressions match reality.]
I'll throw out a straw man for people to discuss (and attack). In theory, all (reasonable) papers start with the same basic grounding -- you have proofs of some theorems. After that point, though, things get a bit hard to judge. How "nice" are your theorems, in terms of technique/mathematical beauty/novelty? How "big" is your improvement over previous work -- for example, is improving an O(log n) competitive ratio to O(log n/log log n) "important" enough? How practical is your solution (hard to say, when nobody actually implements algorithms or gives performance results...)? A lot of this seems subjective, so naturally there are differing opinions.
In networking or other more practical fields, the same issues -- technique/beauty/novelty, quantity of improvement, practicality -- all come into play. But there's a lot more focus on the bottom line of "Could this lead to a substantial improvement for an important real-world problem." Perhaps this consistency in the criterion for what is a good paper leads to more consistency in reviews?
My impression historically has been that there's more variance on the theory side of the world than on the systems side, particularly for the big conferences like FOCS/STOC/SODA. I was amazed, on the whole, at the consistency of NSDI reviews for papers I was on. STOC reviews are coming in, and I'm looking forward to seeing how consistent things are there, but my early impression is that there's not the same consistency, and it's interesting to hypothesize why. [Perhaps, after it's all over, I'll attempt to gather some real quantitative data on the issue, to see if my impressions match reality.]
I'll throw out a straw man for people to discuss (and attack). In theory, all (reasonable) papers start with the same basic grounding -- you have proofs of some theorems. After that point, though, things get a bit hard to judge. How "nice" are your theorems, in terms of technique/mathematical beauty/novelty? How "big" is your improvement over previous work -- for example, is improving an O(log n) competitive ratio to O(log n/log log n) "important" enough? How practical is your solution (hard to say, when nobody actually implements algorithms or gives performance results...)? A lot of this seems subjective, so naturally there are differing opinions.
In networking or other more practical fields, the same issues -- technique/beauty/novelty, quantity of improvement, practicality -- all come into play. But there's a lot more focus on the bottom line of "Could this lead to a substantial improvement for an important real-world problem." Perhaps this consistency in the criterion for what is a good paper leads to more consistency in reviews?
Tuesday, December 30, 2008
New Year's Affirmations
As the New Year beckons, I figured it was time for a post on affirmations, which I remember being interested in when reading about it one of Scott Adams' (of Dilbert) books (though I don't think he called them that). If you haven't heard of affirmations, it's basically the power of positive thinking. There are various forms; one is, take a list of goals you want to accomplish, write them down or repeat them to yourself every day, and you'll find they start happening.
Now, while I don't actually believe that positive thinking alone will allow me to prove P = NP (or the other way) in the coming year -- or, for that matter, win me a lottery! -- I do believe that the act of thinking clearly about the goals you want to achieve, and keeping them firmly in your mind, increases the probability that you will actually accomplish these goals. I personally find that when I set myself goals over multiple time scales -- a task list for the day, for the month, and for the year -- I'm surprisingly much better about getting things done. When I get distracted from setting goals, less happens. The conscious effort of writing tasks down and reminding myself of them makes them easier to accomplish.
So I encourage all my readers to take some time around the New Year and set some tangible, if difficult, work-related goals for the coming year. Maybe it's time to learn a new area or work with that person you've always wanted to work with. Or there's that result you know is just out of reach -- but you should keep reaching for it. Post them somewhere, remind yourself of them, and work to make them come true. I'd bet more do than you'd first think.
Whatever your goals are, best of luck with them, and for the New Year.
Now, while I don't actually believe that positive thinking alone will allow me to prove P = NP (or the other way) in the coming year -- or, for that matter, win me a lottery! -- I do believe that the act of thinking clearly about the goals you want to achieve, and keeping them firmly in your mind, increases the probability that you will actually accomplish these goals. I personally find that when I set myself goals over multiple time scales -- a task list for the day, for the month, and for the year -- I'm surprisingly much better about getting things done. When I get distracted from setting goals, less happens. The conscious effort of writing tasks down and reminding myself of them makes them easier to accomplish.
So I encourage all my readers to take some time around the New Year and set some tangible, if difficult, work-related goals for the coming year. Maybe it's time to learn a new area or work with that person you've always wanted to work with. Or there's that result you know is just out of reach -- but you should keep reaching for it. Post them somewhere, remind yourself of them, and work to make them come true. I'd bet more do than you'd first think.
Whatever your goals are, best of luck with them, and for the New Year.
Tuesday, December 23, 2008
INFOCOM Miniconference
A number of commenters on my last post have mentioned the INFOCOM Miniconference. I hadn't actually known about the miniconference -- although I found out more details about it soon after the comments, as my second INFOCOM submission, rejected from the conference, was accepted to the miniconference. (I did have a paper in INFOCOM 2008, but my student Adam Kirsch went to the conference to deliver the paper, and I can't recall ever hearing anything about the miniconference format. Someone should have blogged about it before. :) )
100 additional papers -- a bit over 7% of the original submissions -- were apparently accepted to the miniconference, covering most of that "top 20-30%" range. The main difference appears to be the labelling (INFOCOM miniconference, not INFOCOM) and that the paper will be limited to 5 pages in the proceedings.
While I'm happy the paper got in, I must admit, I don't understand the reasoning behind the INFOCOM Miniconference, and I hope some readers in the know will explain and elaborate. If the purpose is to have a 2-tier conference, it seems an odd structure -- why not just accept 25-30% of the papers? (A few hundred pages in the proceedings wouldn't seem to matter much since it's on a CD?)
I wonder if theory conferences like STOC, FOCS, or SODA should adopt some sort of 2-tier structure in order to accept more papers. Certainly most people who have papers rejected from these conferences (myself included) believe they should have gotten in, and some fraction of them are probably right. On the other hand, such a structure would seem to lessen the prestige associated with these conferences. Any opinions?
100 additional papers -- a bit over 7% of the original submissions -- were apparently accepted to the miniconference, covering most of that "top 20-30%" range. The main difference appears to be the labelling (INFOCOM miniconference, not INFOCOM) and that the paper will be limited to 5 pages in the proceedings.
While I'm happy the paper got in, I must admit, I don't understand the reasoning behind the INFOCOM Miniconference, and I hope some readers in the know will explain and elaborate. If the purpose is to have a 2-tier conference, it seems an odd structure -- why not just accept 25-30% of the papers? (A few hundred pages in the proceedings wouldn't seem to matter much since it's on a CD?)
I wonder if theory conferences like STOC, FOCS, or SODA should adopt some sort of 2-tier structure in order to accept more papers. Certainly most people who have papers rejected from these conferences (myself included) believe they should have gotten in, and some fraction of them are probably right. On the other hand, such a structure would seem to lessen the prestige associated with these conferences. Any opinions?
Monday, December 22, 2008
INFOCOM paper, network coding
A paper I co-authored on network coding -- Network Coding Meets TCP (arxiv version) -- was accepted to INFOCOM. Full credit for the success goes to the graduate student Jay Kumar Sundararajan who led the project (and is graduating and looking for jobs this year...) Our goal (as the title suggests) is to make a TCP-compatible network coding congestion control scheme, and our approach uses an interesting variation on acknowledgments Jay Kumar had utilized previously; instead of acknowledging packets, you acknowledge "degrees of freedom" (or, encoded packets that will eventually decode to message packets).
The INFOCOM mail said 282 papers were accepted from 1435 submissions (post-withdrawals). A quick check shows that INFOCOM has been below a 20% acceptance rate regularly in recent years, and even assuming a completely unverified estimate that 10-25% of the submissions are things that really shouldn't have been submitted in the first place, in my opinion that's still a pretty low acceptance rate for what's supposed to be the big, open-tent networking conference of the year. (In the 1990s, the acceptance rate was more commonly around 30%.) I'm sure there were a lot of good papers that got rejected this time around.
Most networking conferences have acceptance rates around 20%. Is this a good thing? Conference competitiveness has been blogged about before, but there doesn't seem to be much of a high-level discussion about the issue -- I recently saw Ken Birman and Fred Schneier wrote an article about it for Communications of the ACM. Any ideas out there?
The INFOCOM mail said 282 papers were accepted from 1435 submissions (post-withdrawals). A quick check shows that INFOCOM has been below a 20% acceptance rate regularly in recent years, and even assuming a completely unverified estimate that 10-25% of the submissions are things that really shouldn't have been submitted in the first place, in my opinion that's still a pretty low acceptance rate for what's supposed to be the big, open-tent networking conference of the year. (In the 1990s, the acceptance rate was more commonly around 30%.) I'm sure there were a lot of good papers that got rejected this time around.
Most networking conferences have acceptance rates around 20%. Is this a good thing? Conference competitiveness has been blogged about before, but there doesn't seem to be much of a high-level discussion about the issue -- I recently saw Ken Birman and Fred Schneier wrote an article about it for Communications of the ACM. Any ideas out there?
Thursday, December 18, 2008
What Else Should Grad Students Be Learning?
Apropos of application season...
Graduate school is a long stretch of time -- 5 years (or more) for most people. There are few clear goals during that time, although the obvious one is to learn how to do good research, with the hope of getting a tenure-track faculty job. With this somewhat singular -- and difficult -- goal, it's easy to fall into the extreme of focusing only on your research to the exclusion of most everything else, or to waste a lot of time not really working. Both of these things may be OK for various individuals. (As some will undoubtedly respond, if you're doing great research, it can excuse a lack of many other skills. And many people don't mind spending an extra year at graduate school with a more relaxed lifestyle than life after graduate school.) But with the new year approaching, I thought it worthwhile to suggest some of the additional skills one should try to develop in graduate school over those stretches where you need to break from research -- skills which, unfortunately and understandably, are often given short shrift by the university. (Please add to the list in comments.)
1) Time management: How much are you working each day? (And how much time do you waste reading -- or worse yet, writing -- blogs?) Even if you don't set yourself to a regular 9-5 or 10-6 schedule, it's a good time to learn to manage your working and non-working patterns. My suspicion is that people who manage a regular work schedule graduate on average a semester or year earlier.
2) Writing/speaking: If ideas are our business, idea presentation is a big contributor to the bottom line. And if you want a faculty position, the ability to give a good talk to a general audience goes a long way. If your institution doesn't have a program for improving writing and speaking, start your own (like a student seminar series, no faculty invited).
3) Leadership: Find a way to lead a research project -- maybe advising/mentoring some undergraduates. Or organize a club or student group to make your department a better place to be. Eventually, the ability to organize people to follow your goals will make you more productive.
4) Entrepreneurship: Have you looked at the economy? And professor's salaries? Graduate school is where you're supposed to learn to be creative, and to develop specialized skills. It's quite reasonable to spend some of those creative efforts or utilize those specialized skills on money-making endeavors. While it's not for everyone, for some the tangible reward of money helps unleash creativity; for others, you may learn the satisfying lesson that your intellectual achievements bring you higher rewards than a big paycheck could (a lesson worth learning early on).
5) The skill to learn additional skills: If you're a theorist, learn to program a little. If you're a systems person, learn some probability or other theory. Maybe set aside a few days to learn time-saving Latex tricks, or some other piece of useful software. There are plenty of skills that will make you a better researcher/teacher/writer in the future.
Graduate school is a long stretch of time -- 5 years (or more) for most people. There are few clear goals during that time, although the obvious one is to learn how to do good research, with the hope of getting a tenure-track faculty job. With this somewhat singular -- and difficult -- goal, it's easy to fall into the extreme of focusing only on your research to the exclusion of most everything else, or to waste a lot of time not really working. Both of these things may be OK for various individuals. (As some will undoubtedly respond, if you're doing great research, it can excuse a lack of many other skills. And many people don't mind spending an extra year at graduate school with a more relaxed lifestyle than life after graduate school.) But with the new year approaching, I thought it worthwhile to suggest some of the additional skills one should try to develop in graduate school over those stretches where you need to break from research -- skills which, unfortunately and understandably, are often given short shrift by the university. (Please add to the list in comments.)
1) Time management: How much are you working each day? (And how much time do you waste reading -- or worse yet, writing -- blogs?) Even if you don't set yourself to a regular 9-5 or 10-6 schedule, it's a good time to learn to manage your working and non-working patterns. My suspicion is that people who manage a regular work schedule graduate on average a semester or year earlier.
2) Writing/speaking: If ideas are our business, idea presentation is a big contributor to the bottom line. And if you want a faculty position, the ability to give a good talk to a general audience goes a long way. If your institution doesn't have a program for improving writing and speaking, start your own (like a student seminar series, no faculty invited).
3) Leadership: Find a way to lead a research project -- maybe advising/mentoring some undergraduates. Or organize a club or student group to make your department a better place to be. Eventually, the ability to organize people to follow your goals will make you more productive.
4) Entrepreneurship: Have you looked at the economy? And professor's salaries? Graduate school is where you're supposed to learn to be creative, and to develop specialized skills. It's quite reasonable to spend some of those creative efforts or utilize those specialized skills on money-making endeavors. While it's not for everyone, for some the tangible reward of money helps unleash creativity; for others, you may learn the satisfying lesson that your intellectual achievements bring you higher rewards than a big paycheck could (a lesson worth learning early on).
5) The skill to learn additional skills: If you're a theorist, learn to program a little. If you're a systems person, learn some probability or other theory. Maybe set aside a few days to learn time-saving Latex tricks, or some other piece of useful software. There are plenty of skills that will make you a better researcher/teacher/writer in the future.
Monday, December 15, 2008
NSDI Program Committee , Part II
Some lessons from a 1-day PC meeting (nothing really new, but I thought I'd write it down):
1) Face-to-face PC meetings involve far too much sitting. Especially if you fly in and out on the same day. (I know there's a time tradeoff in scheduling an "exercise break", but seriously...)
2) Conferences with 20% acceptance rates are, by their nature, a bit depressing -- it's hard to reject so many papers, some of which simply MUST be pretty good.
3) It's easier to argue how a paper is flawed than to argue about how it's making an important contribution.
4) Taking reviewer expertise into account is important, and one outlier can cause problems; sometimes papers live on longer than they should if one reviewer gives too high a score, and sometimes papers are put way lower in the ordered list than they should be because one reviewer gives too low a score. (Of course, one expert reviewer can also bring an otherwise ignored paper back to life.)
5) There are more interesting papers than paper slots.
6) There's generally plenty of down time, when papers you didn't read are being discussed; bring something to work on quietly (but pay attention to what's going on).
7) You really do learn a lot reading 20-30 papers for a conference PC.
8) As you go down the paper list by score rank, eventually (and sooner than you think) you hit a paper that you start to question -- are these scores too high? And as you go up the list from the bottom, you'll hit a paper where you question -- are these scores too low? The rules of randomness tell us that some papers will get comparatively mis-scored in the first round of reviews, so it is good to stop and talk about the papers (and not just take the first X).
9) Hot trends come and go.
10) A steady supply of drinks (mostly caffeinated) and a good lunch can help the PC move happily along.
Thanks to the PC chairs and other members -- I had a good time. But now I'm very tired...
1) Face-to-face PC meetings involve far too much sitting. Especially if you fly in and out on the same day. (I know there's a time tradeoff in scheduling an "exercise break", but seriously...)
2) Conferences with 20% acceptance rates are, by their nature, a bit depressing -- it's hard to reject so many papers, some of which simply MUST be pretty good.
3) It's easier to argue how a paper is flawed than to argue about how it's making an important contribution.
4) Taking reviewer expertise into account is important, and one outlier can cause problems; sometimes papers live on longer than they should if one reviewer gives too high a score, and sometimes papers are put way lower in the ordered list than they should be because one reviewer gives too low a score. (Of course, one expert reviewer can also bring an otherwise ignored paper back to life.)
5) There are more interesting papers than paper slots.
6) There's generally plenty of down time, when papers you didn't read are being discussed; bring something to work on quietly (but pay attention to what's going on).
7) You really do learn a lot reading 20-30 papers for a conference PC.
8) As you go down the paper list by score rank, eventually (and sooner than you think) you hit a paper that you start to question -- are these scores too high? And as you go up the list from the bottom, you'll hit a paper where you question -- are these scores too low? The rules of randomness tell us that some papers will get comparatively mis-scored in the first round of reviews, so it is good to stop and talk about the papers (and not just take the first X).
9) Hot trends come and go.
10) A steady supply of drinks (mostly caffeinated) and a good lunch can help the PC move happily along.
Thanks to the PC chairs and other members -- I had a good time. But now I'm very tired...
Sunday, December 14, 2008
NSDI Program Committee , Part I
I'm spending tomorrow at the NSDI (Networked Systems Design and Implementation) Program Committee meeting. It's been a few years since I've been on the PC for a networking conference, but I've found it so far to be a lot of fun.
First, it's very "civilized" -- I had only 20 papers to read the first round, and then had 5 more for the second round. (The first round was designed to get each paper 3 reviews; the second round was for paper missing reviews, or where the scores suggested another review would be helpful.) That's not too much, compared to most theory conferences.
Second, there are a good number of "algorithmically" oriented papers for me to read. Overall, networking has become a lot more theoretical, which is good. It still seems to me, though, for a network-oriented conference, you have to be careful not to go overboard with the theory. They want results -- backed by theory, preferably -- but at the end of the day, it's the results that matter. As usual when serving on a PC, seeing how it works gives insight into how to frame my own papers.
Third, one thing that's impressed me is how long and detailed the reviews are for this conference. I tend to write shorter reviews, covering what I think the high order points are. (And one thing that has been interesting -- there's generally a lot of agreement on these high order points.) But most reviewers go into a lot more detail -- the average review is at least a good page plus of text. Very different than what I usually find in theory conferences -- although I know there's a push to improve that.
I'm not sure why the culture of networking conferences has led to more detailed reviews. Fewer papers per PC member probably helps; maybe because few papers go on to journal papers (but that's equally true in theory, I think). But it's a marked and interesting change.
Anyhow, now I'm looking forward to SIGCOMM... except that I'll need to be ready to write longer reviews.
First, it's very "civilized" -- I had only 20 papers to read the first round, and then had 5 more for the second round. (The first round was designed to get each paper 3 reviews; the second round was for paper missing reviews, or where the scores suggested another review would be helpful.) That's not too much, compared to most theory conferences.
Second, there are a good number of "algorithmically" oriented papers for me to read. Overall, networking has become a lot more theoretical, which is good. It still seems to me, though, for a network-oriented conference, you have to be careful not to go overboard with the theory. They want results -- backed by theory, preferably -- but at the end of the day, it's the results that matter. As usual when serving on a PC, seeing how it works gives insight into how to frame my own papers.
Third, one thing that's impressed me is how long and detailed the reviews are for this conference. I tend to write shorter reviews, covering what I think the high order points are. (And one thing that has been interesting -- there's generally a lot of agreement on these high order points.) But most reviewers go into a lot more detail -- the average review is at least a good page plus of text. Very different than what I usually find in theory conferences -- although I know there's a push to improve that.
I'm not sure why the culture of networking conferences has led to more detailed reviews. Fewer papers per PC member probably helps; maybe because few papers go on to journal papers (but that's equally true in theory, I think). But it's a marked and interesting change.
Anyhow, now I'm looking forward to SIGCOMM... except that I'll need to be ready to write longer reviews.
Friday, December 12, 2008
Summer internships?
The bad economy already has people thinking about jobs -- it is, I am sure, going to be a challenging year (years?) for people graduating.
I was wondering if there would also be an effect on summer internship programs. Summer interns are often a different budget line item, but it's hard to believe that the Microsoft/Google/Yahoo/everywhere else programs, for both undergraduates and graduates, won't be curtailed in this environment.
I haven't heard anything about summer internships yet, and though it's a bit early, late December/early January is usually when I start get reminders from people to have good students apply for the summer. Can anyone comment (anonymously if needed) if they have any actual information?
I was wondering if there would also be an effect on summer internship programs. Summer interns are often a different budget line item, but it's hard to believe that the Microsoft/Google/Yahoo/everywhere else programs, for both undergraduates and graduates, won't be curtailed in this environment.
I haven't heard anything about summer internships yet, and though it's a bit early, late December/early January is usually when I start get reminders from people to have good students apply for the summer. Can anyone comment (anonymously if needed) if they have any actual information?
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