November 2005


Well, it’s about time. “Royal Opera House spokesman Christopher Millard said… ‘It doesn’t work. It’s racially insensitive.’” Ya think?

From PhD Comics and MetaFilter I read about the NYU grad student strike that has apparently started getting ugly.

There are several divisive strategies that the University (read : the Man, the Bosses, what-have-you) has to break the TA union’s efforts to get a contract negotiated. The first is to convince the undergrads to blame the TAs. In a normal strike, many customers will not cross the picket line because they can go to another business. This doesn’t fly in the university setting — students (or their parents) are paying big bucks, and the university can punish undergrads by telling them that their coursework won’t count for this semester if the strike continues. The undergrads will turn around and blame the TAs, lending support for the university’s position.

A second problem is institutional. Graduate students in the sciences and engineering are most often supported by research assistantships for the bulk of their time. TA-ing is considered an obligation for graduation or as a means of support when grant money is thin or you are working on your dissertation. Graduate students in those fields are sometimes ambivalent about the union, because “it doesn’t really affect them.” The GSI (read: TA) union at Berkeley is pretty strong, despite the off-putting sloganeering and obligatory “in solidarity” at the end of every email. I’m very pro-labor, but they use rhetoric that was in vogue back when the Wobblies were news. I know a lot of people who did not join the union simply because they didn’t see the point. The workload for TA-ing varies widely across departments — richer ones hire separate graders, for example. By encouraging this heterogeneity, the inclination to authorize or participate in a strike is reduced.

Finally, the university will invariably give a misleading characterization of the benefits offered to graduate students. Since their whole position is that TAs are students first and employees last, they lump in tuition, fees, and all other benefits as the total compensation given to graduate students. These figures show the truth of the situation — without paying TAs, they wouldn’t get the tuition money anyway and they’d have to hire adjunct faculty who are on average more expensive. But by just trotting out the figures they can make it seem like grad students are handsomely compensated for their time. Again, these figures are for the consumption of undergrads and parents — my tuition is much less since I’m in-state at a public school, and wouldn’t look quite as impressive.

Anyway, more power to the union, and I hope the university comes around.

A new feature! Just to keep myself motivated on research and to dissuade people from reading the blog, I am trying to “read” one research paper a day (-ish) to get the new ideas running around my head. And you guessed it, I’m going to blog the interesting (to me) ideas here.

Denoising and Filtering Under the Probability of Excess Loss Criterion (PDF)
Stephanie Pereira and Tsachy Weissmann
Proc. 43rd Allerton Conf. Communication, Control, and Computing (2005)

This paper looks at the discrete denoising problem, which is related to filtering, estimation, and lossy source coding. Very briefly, the idea is that you have a iid sequence of pairs of discrete random variables taking values in a finite alphabet:

Where X is the “clean” source and Z is the “noisy” observation, so that the joint distribution is p(x,z) = p(x) p(z | x), where p(z | x) is some discrete memoryless channel. A denoiser is a set of mappings

so that g_i(z^n) is the “estimate” of X_i. One can impose many different constraints on these functions g_i. For example, they may be forced to operate only causally on the Z sequence, or may only use a certain subset of the Z‘s or only the symbol Z_i. This last case is called a symbol-by-symbol denoiser. The goal is to minimize the time-average of some loss function

This minimization is usually done on the expectation E[L_n], but this paper chooses to look at the the probability of exceeding a certain value P(L_n > D).

The major insight I got from this paper was that you can treat the of the loss function

as outputs of an source with time varying (arbitrarily varying) statistics. Conditioned on Z^n each h_k is independent with a distribution in a finite set of possible distributions. Then to bound the probability P(L_n > D), they prove a large deviations result on L_n, which is the time-average of the arbitrarily varying source.

Some of the other results in this paper are

  • For a Hamming loss function the optimal denoiser is symbol-by-symbol.
  • Among symbol-by-symbol denoisers, time-invariant ones are optimal.
  • An LDP for block denoisers and some analysis of the rate.

Most of the meat of the proofs are in a preprint which seems to still be in flux.

I’m not hot-shot enough to be asked to review papers yet, but I’ve looked over a few for others who wanted a second take on things, and it seems that the backlog of reviews, especially for conferences, is enormous. Here’s a set of recent (and not so recent) comments on the peer review process:

Larry Wasserman talks (from experience) about the problems of hostile reviewers and nasty politics.

Cosma Shalizi says there are many many more reasons to reject a paper than Wasserman, but that peer review should be reader-centric in focus.

David Feldman thinks that journals should give out free socks or something to reviewers so that there is at least some token appreciation of all the work they put into it.

Martin Grossglauser and Jennifer Rexford have another good take on the system.

Fundamentally it seems there are two problems to solve — reviewers have no incentive to review papers quickly, and the objective of the reviewing process is rarely articulated clearly. Socks and pools both seem like good steps in that direction. It seems to be one of those situations where trying small fixes now would be much better than trying to institute some huge shift in editorial processes across many journals all at once.

As promised, the first in two posts responding to Manjula Padmanabhan’s follow-up criticism of our production of her play Harvest at UC Berkeley. She labors under the misapprehension that we need her approval and benediction. This is absurd — everyone is entitled to their opinion, and if she didn’t like the performance then that’s fine. It is nice, of course, to have people like the work, but her backhanded praise (“the actors were very gifted; it isn’t their fault that they were encouraged to over-act recklessly”) and patronizing tone certainly don’t earn her points in my book.

I firmly believe in the prerogatives of the writer as long as they are willing to act on their objections. Unfortunately, Padmanabhan is unwilling to recognize the possibility that her play may be less than clear stylistically:

It is hard therefore, for me to understand the need for me to specify what I want from a production. I already know, from past experience, that some directors succeed in interpreting the script appropriately.

In other words, because someone else thinks the way she does, clearly everyone should reach that same “correct” conclusion. It’s a very appropriate attitude, given our contemporary political atmosphere in this country. Why start a dialogue when you have at least one supporter?

Now that she is safely validated by one production and three readings, she has eaten her cake. However, she says:

It’s not true that once a play has been written and published it is automatically “out there” for the world to do with it what it likes… So long as the playwright is still alive, it is considered quite normal for him/her to exercise some control over how the work is performed.

But she does not excercise this control. She has had problems with interpretations of her play before — does she merely go into every production offer, wide-eyed and full of naivete? No, her policy is “don’t ask, do tell.” She does not ask about the aims and aesthetics of the production, and she does tell people that the authorial intent, so clearly seen by at least one director, has been deliberately bypassed. Having eaten her cake in one production, Padmanabhan wants to have it as well.

Padmanbhan throws in a few platitudes that once she realizes that “a production that has set off down the wrong path” she still wouldn’t want “to object and to insist that it be done differently,” because “it’s kinder to permit the show to go on.” These are nice sentiments, but short of withdrawing her contract granting the rights to the production, there is little she can do in those situations. What undercuts this highmindedness is that after the first weekend she withdrew her permission to have the production videotaped, so I will never get to see my own performance in which I “over-act recklessly.”

I have already addressed the issue of her instructions within the text in my previous post. However, she believes the real problem to be that

some directors believe in allowing a play to breathe on its own, while others try to force their own breath into it. The first variety is wonderful to work with — and I have no difficulty accepting the minor cuts and/or additions such directors might request. The directors interpreted my script in a straightforward manner and didn’t add any unexpected flourishes to the existing text. The result was cool, austere and true to my intention; a happy place for all concerned to be in.

Padmanabhan writes of the director as an enabler, a technician who facilitates the embodiment of the text. This limited view of directing runs counter to the more modern (as modern as automobiles) idea of the director as a creative artist. She thinks of this as a difference of an “internal” intent that she has placed in the text versus and “external” intent imposed by the reader. But the play is in the end merely a collection of words, and the intent or interpretation she ascribes to it is her own “external” intent, validated by her authority as author. If she really wanted to be clear about her own intent, she could easily write some prefacing remarks about how the play should be performed exactly, following the script to the letter.

To her, this is completely unncessary, because some directors have produced the “cool, austere” production that she desires. Fundamentally, Padmanabhan believes that newer text should be privileged over older text:

I believe it’s because they don’t allow the text to breathe. When they’re performing familiar, classic plays, it doesn’t matter because the audience already knows what the original is like. The problem arises when they approach new work. In such situations, what they produce can appear to be what the playwright intended.

In her world, only those “classic” plays (what is classic?), the plots of which are universal or whose “original intent” is known by the audience (who is the audience?), are open game for non-authorial interpretations. Her fear is that any production that doesn’t conform to her view of the play is an inaccurate representation. Instead of excercising some artistic control, she says “one has just got to grit one’s teeth and let the thing run.”

Despite all of my nitpicking about her complaints, I am sympathetic to the underlying dissatistfaction that fuels Padmanabhan’s comments. It is incredibly frustrating to be misunderstood, especially if your ideas have been validated in a previous production. However, she cannot seem to make up her mind about how to deal with this disappointment. Indeed, she believes she shouldn’t have to do anything, not even exercise choice over where and how her work is performed. Instead she accuses others of acting in bad faith in an attempt to keep control of the interpretation after the performance. How can we view this other than having her cake and eating it too?

In case you were wondering what I’m working on (sometimes I wonder myself), the 2006 ERL Research Abstracts have been posted. Now to actually do the work that I’m claiming to do…

My old edibles blog has been folded into the main blog — once I figure out how to get link bar working properly they should appear there. Maybe that will encourage me to write more food commentary.

Update: WordPress lets you make static pages external to the blog itself but using the same stylesheet. The Edibles section is now available from the top navbar as well as the sidebar.

Since I was updating the old blog anyway, I figured I’d try out some nify new features that people have developed, like MimeTeX, which is a cgi script that renders LaTeX on the fly for you and doesn’t have any other dependencies. So now I can write about things like the Gaussian distribution:

Although it might be a bit hard to use expressions that are too fancy and use all the crazy squiggles and arrows that come with the AMS packages, this is definitely a step up in the world of blogging math.

I will be migrating to WordPress shortly. After doing so I will blog about Manjula Padmanabhan’s latest comments on Harvest in two parts : “The playwright has her cake and eats it too” and “Identity, authenticity, and universality.”

Update: migration seems to have been successful, but I need a less godawful template. Aesthetic sensibilities will be restored pending actual sleep.

After government, he wants to go back to writing. I was given a book of Havel’s plays when I was in high school, and some of them are pretty good. Unfortunately, I missed out on seeing the production that Deb assistant directed in SF, so I’ve yet to see anything of his staged.

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