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MACHINE LEARNING, COMPUTER SCIENCE, JAZZ, AND ALL THAT

Science and the Market Metaphor

John Langford had an interesting post on what he calls the “adversial viewpoint” on academia. Basically, the argument is that under this viewpoint, you assume that scientists in academia compete over a fixed set of resources (research money, positions, students) and that therefore all the other scientists are your adversaries. He suspects that this might be one of the reasons behind the decline in reviewing quality at conferences such at NIPS he has observed in the following years.

John argues that the adversarial viewpoint might make sense, but it is actually bad for science, because scientists are more focused on rejecting other papers, projects or ideas, instead of being open for new developments.

I’m not sure whether the variable quality of NIPS reviews is really due to the enormous popularity of the NIPS conference and the load this puts on the program committee and the reviewers, or if it is because people are actively destructive about their peers work.

But I think this leads to an interesting question about the environment in which academia exists, why it is like it is and how it could be changed to lead to different viewpoints. Because if it really is a zero sum game, then it is not surprising that those who want to play the game successfully adopt an adversarial viewpoint.

A Simplified History of Public Funding for Scientific Research

I’m really not an expert in history of science, but I guess it’s not completely wrong to say that the way science is embedded and supported by society has changed dramatically in the 20th century. Beginning with the industrialization and in particular during World War II it became apparent that having a productive scientific community is absolutely vital, both to the overall growth of your economy, but also for national security. For example, the National Science Foundation was created specifically after World War II with that goal in mind.

Naturally, if it was that important, the government had to take control and set up ways to maximize the scientific productivity (because it had to make sure that the tax payer’s money is used well). While in historic times, scientists were selected by personal preferences and paid by some rulers to work at their court, managing science and setting up the rules of the games more and more became a responsibility of politicians.

Applying the Market Metaphor to Science

The problem was of course that science had never been organized on this level, in particular not by non-scientists. The question basically was: How can we maximize the scientific output from a fixed amount of resources. I think this is a very important question, and I’m certain the optimal answer hasn’t been found yet. Looking at how science is organized today, it seems that they resorted to transplanting a well known metaphor, that of a free market, where scientific ideas and research plans compete over grant money, slots in publications, and positions.

You can find this idea in many different aspects. For example, a grant call is like a customer expressing a certain need, and then companies (that is, scientists) can compete for that money and the one who offers the best research for that money will get it. I’m not saying that this is not a good way to select who to fund, but grant calls are used as a device to control the direction in which science progresses, and the question is whether this ensures the overall progress of science.

Another example is the way in which the scientific output is measured by citation counts. A scientists (=company) produces a scientific publication (=goods). Such publications are then put on show in journals (=stores) where other scientists can cite them (=buy them). The productivity of a scientist is then measured by the amount of goods sold where the quality of the store factors into the price paid by other scientists.

Science is not Economy

I’m not saying that this system does not work at all, but science and scientific research in particular have properties which conflict with the economic setup.

For one, as in art, there is an independent notion of quality for scientific work which is somewhat independent from whether it competes well in the market. For example, it might be a brilliant piece of work, but there is only very little intersection with what other people are working on right now. Or it is not what the funding agencies are focusing on right now. I think every scientist has at least once experienced the conflict between what he considers good scientific work and what he has to do to get grant money. Or put even differently, if everyone would just play the game (publish papers, get grant money, basically secure his position in the field), would that alone ensure scientific progress?

Moreover, what gets published in journals is mainly managed through the peer reviewing processes. Translated to economy, this means that your competitors have a lot of say in whether your products will actually see the market. Assume that before Apple sells its new laptops, the store will first ask Microsoft, Dell, and HP what they think of the laptops? It is clear that it’s hard to do differently in science, because the you need a lot of expertise to judge whether a paper is worth publishing, which cannot be done by the store owner alone, but still, this setup introduces a lot of interaction not present in a truly free market.

In science, significant progress often comes from sidetracks. While most people are working on extending and applying a certain scheme, now approaches are often found elsewhere and take some time before they can enter the mainstream. However, a mass market (and given the number of scientists today, it certainly is a mass market) tends to produce products for the masses, and it is unclear whether a remote idea could really get enough support to work.

Science as a whole is progressing, I guess, but I believe it partly is because people manage to play the game and do the research which matters to them at the same time.

A Way Out?

I have to disappoint you right away, because I do not know the solution. But I think actually seeing the difference between a free market and science is important, and I hope it will make you think.

Others have been more brave in this respect. For example, people have thought about how to allocate money in a way which prevents us to just feed the “mass market” and also allow small independent research projects. Lee Smolin suggests an alternative way to distributed grant money in his book “The Trouble with physics”. Siegfried Bär in his book Forschen auf Deutsch (Research in German) also suggests how to improve the way research money is distributed in German. I won’t go into detail here, but both researchers think that the whole proposal writing business just takes up too much time, and the process should become much more flexible such that more researchers have time to actually do research, and also on the topics they are interested in. Part of the money should even be spent on ideas which really don’t seem that relevant (but to scientists which have otherwise proven not to be crackpots).

If you in principle agree that citation count is a good measure of scientific progress, and you believe in the market, then the problem remains that the scientific publication culture is different from a real market because your competitors can veto that the customers see your product at all. The question boils down to how to improve the reviewing process. Marcus Hutter has archived an email discussion from 2001 on his homepage on what alternatives there are to the existing review process. John Langford suggests to also use preprint servers like the arxiv to get a time-stamp for your work, since you cannot be sure when you will manage to get it published.

I think people have naturally been thinking about improving the review process because in the age of the Internet, this is actually something we as scientists can actively control (as opposed to controlling funding policies). The whole system already depends on unpaid volunteers, so we should have enough manpower to run any other system as well if it gets enough support.

I’d like to repeat the idea of Geoffrey Hinton from the above email discussion. He proposed a system where people put endorsements for papers on their homepages, together with a trust network you define for yourself. You register other scientists whose opinions you trust when it comes to which papers are worth reading. In 2001, the setup was personal websites and a tool, but nowadays, you would certainly turn this into some Web2.0 application. citeulike seems to go in that direction, although the focus is currently more on organizing what papers you have read.

In essence, the goal is to make the path from company to customer much shorter, and in particular, to lessen the impact of your competition on whether your customer can buy your products, that is, cite your papers, or not.

Conclusion

So in summary, I think the framework within academia lives is not altogether bad, but there is always room for improvement. Currently, the market metaphor is often applied blindly without taking account the peculiarities of scientific research, or the scientific community as a whole. The perception that academia is basically a zero-sum game as voiced by John Langford is directly based on the idea that science is a competition over fixed resources. As I have pointed out, the main difference is that science is also a bit like art to the extent that it has it’s own internal notion of quality and soundness which cannot be easily grasped or measured in terms of economic concepts. If we could manage to integrate these different aspects of science we might be eventually able to find better ways to run academia.

Update (Jan 30, 2009): I found an interesting blog post by Michael Nielsen. His basic argument is that we not only need new ways of exchanging, archiving, and searching existing knowledge, but also a radical change of culture, potentially backed by new online tools. For example, he argues that it would be highly advantageous if scientists could easily post problems they are stuck on and quickly find other scientists who are experts on those problems. However, people might only be willing to do this if such contributions would be tracked the same way peer-reviewed publications are.

Interestingly, I see some parallels between these ideas and the way we have been setting up mloss.org and the Open Source Software Track at JMLR. We have provided both the tool, and a means to make publishing open source software accountable under the old metrics - peer-reviewed publications.

On NIPS 2008

Although I came home from last year’s NIPS conference more than three weeks ago, I haven’t yet found time to summarize my impressions. I’ve found that it’s always like this, first there is the jet-lag, then there is Christmas, New Year.

But maybe it’s not just the closeness to the holiday season, I think it’s also that NIPS is so content-rich that you really need some time to digest all that information.

Banquet Talk and Mini-Symposia

This year, in particular, because they have managed to cram in even more session into the program. They used to have some invited high-level talk during the banquet in previous years, but this year the organizers have chosen to put two technical talks and virtually 20 poster spot lights during the banquet. Actually, I’m not that sure whether this decision was wise as I and most of my colleagues felt that dinner and technical talks don’t go well together. Maybe it was also my jet-lag, as I arrived on Monday afternoon, not on Sunday like some people.

The second addition where the mini-symposia on Thursday afternoon, conflicting with the earlier buses to Whistler. I attended the computational photography mini-symposium and found it very entertaining. The organizers have managed to put together a nice mix of introductory and overview talks. For example, Steve Seitz from the University of Washington had a nice talk on how to reconstruct tourist sites in Rome from pictures collected from flickr. Based on these 3d reconstruction you could go on a virtual tour of famous monuments, or compute closest paths based on where pictures were taken.

So if I had anything to say, I’d suggest to keep the mini-symposia, but replace the technical talks during the banquet by the invited talk as in previous years.

Presentations

With over 250 presentations, it’s really hard to pick out the most interesting ones, and as the pre-proceedings aren’t out yet (or at least not that I’m aware of), it’s also hard to collect some pointers here.

There was an interesting invited talk by Pascal Van Hentenryck on Online Stochastic Combinatorial Optimization. The quintessence of his approach to optimization in stochastic environments was that often, the reaction of the environment does not depend on you the action you take, so you can build a pretty reliable model for the environment and the optimize against that.

Yves Grandvalet had a paper “Support Vector Machines with a Reject Option”, which proposes a formulation of a support vector machine which can also opt to say “I don’t know which class this is”.

John Langford had a paper which was already a preprint at arxiv.org on sparse online learning which basically has the option to truncate certain weights if the become too small.

Every now and then there was an interesting poster with nobody attending it. For example, Patrice Bertail had a poster on “Bootstrapping the ROC Curve” which looked interesting and highly technical, but we could find nobody. At some point I started to discuss the poster with a colleague, but we had to move away from the poster after people started to cluster around us as if one of us were actually Patrice.

Michalis Titsias had an extension of Gaussian Processes in his paper “Efficient Sampling for Gaussian Process Inference using Control Variables” to the case where the model is not just additive random noise but actually depends non-linearly on the function where the Gaussian process is on. It looked pretty complicated, but it might be good to know that such a thing exists.

There were many more interesting papers, of course, but let me just list one more: “Adaptive Forward-Backward Greedy Algorithm for Sparse Learning with Linear Models” by Tong Zhang seemed like a simple method which combines feature addition with removal steps and comes with a proof (of course). I guess similar schemes exist in dozens, but this one seemed quite interesting to try out.

The question I always try to answer is whether there are some big new developments. A few years ago, everybody suddenly seemed to do Dirichlet processes and some variant of eating place. Last year (as I have been told), everybody was into deep networks. But often, I found it very hard, and this year was also one of those. Definitely no deep learning, maybe some multiple kernel learning. There were a few papers on which try to include some sort of feature extraction or construction into the learning process in a principled manner, but such approaches are (necessarily?) often quite application specific.

I also began to wonder whether a multi-track setup wouldn’t be better for NIPS. This question has been discussed every now and then, always in favor of keeping the conference single-track. I think one should keep in mind that what unites machine learning as a community are new methods, because the applications are quite divers, and often very specific. For a bioinformatics guy, a talk on computer vision might not be very interesting, unless there is some generic method which is application-agnostic to a certain degree.

It seems that currently, most of the generic methods are sufficiently well researched, and people now start to think about how to incorporate automatic learning of features and preprocessing into their methods. As I said above, such methods are often a bit ad-hoc and application specific. I’m not saying that this is bad. I think one first has to try out some simple things before you can find more abstract principles which might be more widely applicable.

So maybe having a multi-track NIPS would mean that you can listen more selectively to talks which are relevant to your area of research and the list of talks wouldn’t appear to be somewhat arbitrary. On the other hand, you might become even more unaware of what other people are doing. Of course, I don’t know the answer, but my feeling was that NIPS is slowly approaching a size and density of presentations that something has to change to optimize the information flow between presenters and attendees.

Workshops

I’ve heard that some people come to NIPS only for the workshops, and I have to admit that I really like them a lot, too. Sessions are more focused topic-wise, and the smaller size of the audience invites some real interaction. Whereas I sometimes get the impression that the main conference is mostly for big-shots to meet over coffee-breaks and during poster sessions, it’s in the conferences where they participate in the discussion.

We had our own workshop on machine learning and open source software which I have summarized elsewhere.

I attended the multiple kernel learning workshop which really was very interesting, because most of the speakers concluded that in most cases, multiple kernel learning does not work significantly better than a uniform average of kernels. For example, William Stafford Noble reported that he had a paper with multiple kernel learning for the Bioinformatics journal, and only afterwards decided to check whether unoptimized weights would have worked as well. He was quite surprised when the differences where statistically insignificant and concluded that he wouldn’t have written the paper in that way had he known the results before.

Francis Bach also gave a very entertaining talk where he presented Olivier Chapelle’s work, who couldn’t attend. He did a very good job, including comments like “So on the y-axis we have the relative duality gap - I have no idea what that is”, and raising his hand after his talk to have the first question.

All in all, I think this workshop was quite interesting and exiting and also important for the whole field of multiple kernel learning, basically, to see that it doesn’t just work, and to try to understand better when it doesn’t give the improvements hoped for and why.

Finally, many workshops were taped by videolectures.net. I’ve collected the links here:

On my way to NIPS 2008

Next week is the annual NIPS conference in Vancouver. In case you don’t know, it’s one of the most important annual conferences in the area of machine learning. It’s actually its 22nd installment, and while the full title (Neural Information Processing Systems) hits at the beginnings of the fields with artificial neural networks, such methods cover only a small percentage of the presented papers nowadays.

Together with Soeren Sonnenburg and Cheng Soon Ong we have organized a workshop on machine learning open source software. I’m pretty excited about our program, I only fear that our decision to drop the coffee breaks in favor of a few additional talks will backfire severly. But we’ll see.

I plan to use my twitter account this year to cover the workshop, so if you’re interested, make sure to have a look. Most importantly, I will cover our workshop so that you can see how far we are behind schedule. ;)

By the way, the picture above shows the swimming gas station. It mostly services seaplanes, and you have a very nice view of it from the top floor of the hotel where the NIPS conference takes place.