End-of-year roundup

A few end-of-year items:

• I was in York (that's York, UK) a couple of weeks ago to attend Bionetics. I presented the following paper, in which we move beyond analysis of active transport molecular communication, and get into channel design:

• N. Farsad, A. W. Eckford, and S. Hiyama, "Channel design and optimization of active transport molecular communication," in Proc. 6th International ICST Conference on Bio-Inspired Models of Network, Information, and Computing Systems, York, UK, 2011. [PDF]

• Early in the new year I'll be attending this workshop at BIRS. It looks even more tempting than the January skiing in Banff, and I'll try to blog about it if I find the time.

• The EE program proposal, part of York's rapid engineering expansion, is grinding away -- it's about to go up for approval by the School of Engineering. Meanwhile, here's our first job ad. We're focusing on electronics, power, and medical devices in this round, but we plan to add signal processing and communications spots later (and maybe now, if we get a truly outstanding candidate). Tell your friends!

Happy holidays / Joyeux fêtes, and I'll see you in 2012.

Weird Sun Media - York U Internet Problem (Update 2)

Are you at York University right now? Quick, try to connect to torontosun.com, ottawasun.com, winnipegsun.com, calgarysun.com, and edmontonsun.com.

Add a comment below (or email aeckford@gmail.com if you don't want it to be public) with the following info:

1. What do you see?
2. What's your computer, operating system, and browser?
3. What's your IP address? (fastest way to find it: use Google)

I'll update when I find out more.

Update Dec. 3: The outage is fixed! I got a call from Sun Media's Director of Networks, Telecom, and Information Security. He asked me to send some technical details, and their tech team seems to have solved the problem. It's not clear what happened, but the director mentioned that it might have been in response to hacking attempts, as I suspected. (Meanwhile, the only response I got from York's UIT was to close my support ticket without explanation.)

Update Dec. 1: The outage is real. I can't reach the Sun papers from either of the computers in my office (in the cse.yorku.ca subnet), nor can I reach them when I connect to AirYork. The outage has lasted several days at least. However, the outage is not universal to Sun Media sites (listed here). Only the above five sites are affected.

If I were Dean of Graduate Studies: Rethinking the PhD

With the departure of Douglas Peers to Waterloo, York University is now looking for a new Dean of Graduate Studies. So let's say I put my resume in, and let's also say all the other candidates got struck by lightning. What would I do if I were Dean?

I've sat on the graduate faculty council, so I'm well aware that the nuts and bolts of graduate administration is mundane; even the controversies are kind of boring. But as your new Dean of Graduate Studies, I would address an issue that I don't see discussed very much: what should a graduate faculty be teaching?

UPDATED: Big news for York Engineering

UPDATE Nov. 2: York science librarian John Dupuis livetweeted the event (and collected a summary of tweets here). From John's blog:

I did a ton of live tweeting of the announcement, some of which is here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here and here. The most significant new information revolves around naming the new engineering school The Lassonde School of Engineering. As well, what is now the Computer Science and Engineering Building will be known as the Lassonde Building.

Original post follows.

Canadian entrepreneur Pierre Lassonde is donating $25 million to expand engineering programs at York University. The donation will be matched by the university, and combined with the earlier announcement of $50 million for a new engineering building, that makes a total of $100 million for engineering expansion at York. We've been told that Lassonde's contribution is the largest single private donation in university history.

The official announcement will happen today at 1 PM, but in the meanwhile you can read more about the donation in this Globe and Mail story.

With the donation, the university's goal is to move away from the "niche" engineering programs currently in the program, and become a full-fledged "traditional" engineering school. You can expect York to add traditional engineering disciplines like civil, mechanical, and chemical over the next few years.

However, it's electrical engineering that will take the lead in expansion. I am chairing the committee that will write the EE proposal, and we're operating under the assumption that the first students will be admitted in 2013.  I'll try to blog more about our progress as things develop.

For now, it's definitely an exciting time to be at York.

UPDATED: Talk at Case: Models and Capacities of Molecular Communication

Updated Oct 26, 2011: Here's the video of the talk (this is a playlist). Try HD (720p) and fullscreen, which makes it easier to read the slides.

Original post from October 13 follows.

I'm continuing my 2011 "lecture tour" with a visit to Case Western Reserve University in Cleveland, Ohio. My host is Prof. Peter Thomas, and he would be able to give you further details.

"Models and Capacities of Molecular Communication"

Friday, October 14, 11:30 AM

Abstract: What are the fundamental limits of diffusion-mediated molecular communication? This question, which has only recently attracted attention from information theorists, turns out to be surprisingly difficult. Not only is the communication medium unfamiliar to communication engineers; but the mathematical details of the communication environment are complicated. In this talk, we discuss mathematical models for molecular communication, which are both information-theoretically useful and physically meaningful; we discuss the difficulties of dealing exactly with these models; and we present some simplified scenarios in which capacity can be evaluated.  Finally, we discuss the engineering and biological significance of these results.

Fixing undergraduate education

Here's Jeffrey Simpson's column this past Friday -- his latest in a series (1, 2) taking universities to task over undergraduate education. (The Globe seems to be on a tear lately about our "unsustainable" universities.)

I seem to live in a different world than Simpson's hard-luck undergrads: in my program, classes are small and are (almost) all taught by full-time, tenure-track faculty. The small classes probably come from the newness of our program -- we're expecting to ramp up enrollments over the next decade. But the use of full-time faculty in teaching is more or less universal at Canadian engineering schools. Why is that? It's partly because engineers with PhDs can get lucrative jobs, so perma-adjuncting is not very attractive. But it's also because you need a license to teach engineering in Canada -- licenses are tough to get, and until very recently you couldn't get one if teaching was your only work experience.

So here's something the provincial government could do, which would cost very little up front: require teachers at public universities to be licensed, much as public school teachers are. As a condition of the license, the province could require a course or two on teaching at the postsecondary level (something very few professors have ever received -- right now it's a learn-on-the-job kind of situation). The province could also distinguish between "adjunct" licenses and "tenure-track" licenses, and require at least some minimum fraction of education hours be given by tenure-track license holders.

This kind of solution strikes me as much easier to implement than trying to strong-arm universities into opening up collective agreements with faculty, as Simpson seems to want. It wouldn't do much about class sizes, but that is more of a monetary issue.

Of course, I disagree fundamentally with Simpson's view of the university -- particularly his disregard for research and graduate education -- but that's a topic for a different post.

Stimulus, Response: The G&M on Universities in Canada

On Tuesday, the Globe and Mail called out Canadian universities for their poor undergraduate teaching, calling current practices "unacceptable" and "unsustainable".

Here's one of many twitter discussions it triggered, letters to the editor (scroll to "Connecting the Dots"), and blog-length responses by Melonie Fullick, OCUFA, and Worthwhile Canadian Initiative.

There's lots of good stuff to read there, and I only have this to add: the Globe editorial frames the problem in terms of tension between research and teaching, and disregards any role for the modern university beyond the training of undergraduates. This is consistent with positions expressed by their senior columnists, Jeffrey Simpson and, more outrageously, Margaret Wente (seriously, go read Wente's column if you haven't already).

The "tension" between teaching and research is about as real and helpful as the War on the Car. Strong research programs help faculty keep their teaching dynamic, current, and topical; besides which, graduate-level teaching (like supervision of a Ph.D.) is research, and is totallly ignored by the Globe. So let's please put to bed this corrosive idea that research is some kind of luxury, or an optional activity that can be cut without consequences. (Again, where have we heard this kind of simplistic thinking before?)

[h/t @qui_oui for the links]

Talk in Kobe: Information-theoretic problems in molecular and nanoscale communication

I'm in Osaka right now on a research trip, getting caught up on my many Japanese research contacts. One of the items on my agenda is a talk in Kobe on Monday afternoon, at the Kobe Advanced ICT Research Center, part of NICT. Details:

Title: Information-theoretic problems in molecular and nanoscale communication

Abstract: Recent advances in MEMS/NEMS and systems biology have made it possible to manufacture customized nanoscale devices, such as swarms of nanorobots. However, manufacturing is not enough: a significant remaining challenge is to solve the communication problem among these devices, which would allow them to coordinate their actions. Furthermore, the nanoscale communication environment is rather different from the systems that are usually studied by information and communication theorists. In this talk, I will introduce the nanoscale communication problem from an information-theoretic perspective, focusing on molecular communication, which mimics the way in which microorganisms communicate. Mathematical models and achievable-rate results will be presented, and important open problems will be discussed.

[Link for further details]

The ICC Deadline Fiasco

ICC is one of ComSoc's "flagship" conferences, and I try to submit something every year. It is more or less an annual tradition that the submission deadline is extended at least once. And although extensions are widely expected, they are never certain -- the conference organizers use the magic words (see here):

The Conference TPC has set realistic deadline dates and these may be rigorously adhered to.

This year, the original deadline was on Tuesday, September 6. Late in the evening of September 6, the first extension was officially announced by email, to September 19. And this morning, after working late into the night to get our paper finished, I noticed (not by email -- there has been no official announcement as yet -- but by logging in to EDAS) that the deadline has again been extended to September 28.

To be fair, the extensions have been useful.  We were having trouble getting good results out of our simulations, and without the first extension, we wouldn't have had a paper. But it is really annoying that the extensions were announced with only a few hours to go before the deadline. In the most recent case, I spent the weekend working late, and cleared my Monday schedule to make extra time to hit the deadline. For people like me with families and busy jobs, that causes a lot of tension.

I've never served any high-up role on a large TPC, so I don't know how extension decisions are made. But I don't think it's too much to ask that the extensions be announced with 48 hours' notice. It's not nice to let people ruin their weekends for no reason.

UPDATED: Paper at PIMRC: Hardware implementation of fractional cooperation

Update Sept. 15, 2011: PDF of the paper is here. Citation:

A. Calce, N. Farsad, and A. W. Eckford, “An experimental study of fractional cooperation in wireless mesh networks,” in Proc. 22nd Annual IEEE Symposium on Personal Indoor Mobile Radio Communications (PIMRC), Toronto, ON, pp. 990-994, 2011.

Original post follows.

I've got a paper at this week's IEEE PIMRC in Toronto:

A. Calce, N. Farsad, and A. W. Eckford
An experimental study of fractional cooperation in wireless mesh networks
Session: LPAN-8 (Multihop Cooperative Communication)
Date: Tuesday, September 13, 10:30-12:00
Room: Pier 9

Over the past five years I (and a bunch of other researchers, like Ravi and Nariman) have done a pile of work on fractional cooperation. Under this scheme, cooperation partners can just show up, relay as much of your transmission as they feel like (selecting symbols from your frame randomly), and leave -- with very little protocol and essentially no coordination. As chaotic as this sounds, we have always been able to show good results in simulation.

But with this paper, we put fractional cooperation in hardware for the first time: using some spare iMotes we had in the lab, my student Anthony managed to put together a small mesh network, showing that the system works as well in practice as it always has in MATLAB.

I'll post PDFs soon. Anthony will be giving the talk.

Designing microchannel molecular communication systems: Paper in Nano Communication Networks

I've got a new paper in Nano Communication Networks. (Of the five journal papers I've co-written on molecular communication, this is the last to be submitted and the first to be published ... quick review process FTW. But on the other hand, it's published by Elsevier.)

N. Farsad, A. W. Eckford, S. Hiyama, and Y. Moritani, “Quick system design of vesicle-based active transport molecular communication by using a simple transport model,” Nano Communication Networks, doi:10.1016/j.nancom.2011.07.003, 2011. [PDF]

In this paper, we're continuing our work on microchannel molecular communication (see also here), where molecular motors are used to transport the message-bearing molecules (MBMs).

Generating Lévy random variables from Gaussian (Updated)

Update August 17, 2011: Corrected a typo in the distribution.

Sometimes when I learn a neat mathematical trick, I write a blog post so I don't forget it.  This is one of those times.

If a random variable x has the Lévy distribution with parameters c and μ, then the pdf of x is given by

This distribution has applications in economics, finance, and physics. A famous statistical application is the first passage time of a Brownian motion: if w(t) is given by the Wiener process (with initial condition w(0) = 0), and x is the first time that w(x) = d, then x is Lévy distributed with c = d^2 and μ = 0.

Here's the trick, which is hard to find in the literature: let z represent a Gaussian-distributed random variable with mean 0 and variance v. Then 1/z^2 is distributed Lévy with c = 1/(2v^2) and μ = 0. In other words, if you have a good Gaussian random number generator, you can use it to quickly generate Lévy-distributed random variables!

This property is very briefly mentioned in the following paper (I had to do a bit more digging to verify it and get the right parameter values):

J. M. Chambers, C. L. Mallows, and B. W. Stuck, "A method for simulating stable random variables," J. Am. Stat. Soc., vol. 71, no. 354, pp. 340-344, Jun. 1976.

Talking about wireless: Elizabeth May's advice

Green Party leader and Member of Parliament Elizabeth May recently caused a stir by expressing concern over the safety of electromagnetic radiation. And here she is again this past weekend, taking an interview with her BlackBerry set to speakerphone, to avoid radiation exposure.

I'm not going to go into her concerns about safety (with which I largely disagree; if you're interested in the debate, an excellent summary is here). At the very least, May makes the valid point that there is no scientific consensus on wireless safety.  Fair enough!

But in her longer critique of wireless safety (found here on her blog), and by way of her subsequent actions, May gave some advice to those who are concerned about their exposure to EM radiation. Paraphrasing, she said this:

1. When using your phone, use speakerphone or text rather than holding it up to your ear.
2. You can use a smartphone, but don't keep it in your pocket.
3. At home, use a wireline network, not WiFi.
4. Don't get a Smart Meter.

What I will talk about is this: for people who are concerned about radio exposure (which doesn't include me), did Elizabeth May give good advice? It seems to me that #1 is good advice, #2 and #3 are questionable, and #4 is wrong to the point of embarrassing.

First Shannon Award Livetweet

Announced moments ago at the ISIT 2011 banquet in St. Petersburg, Russia: Congratulations to Abbas El Gamal on his well-deserved Shannon Award.

Livetweeted from the event by Johann Briffa:

And now a word from our sponsors (repost)

(This post was originally published in March, but was taken down as -- unknown to me at the time -- the results of the Discovery competition were under embargo. Now that the results are public, I'm republishing the post.)

NSERC Discovery results came out yesterday.  This is the program that supports almost all of the curiosity-driven, non-industrial, basic science and engineering research in the country.  It's generally not a huge amount of money -- enough to pay 1-2 graduate students is typical.  But most Canadian professors hold one, and it probably pays the salary of the majority of Canada's science and engineering graduate students.

Just now, a summary of the competition landed in my inbox.  By now, the "new regime" of Discovery funding is well known: applications are assigned a quality score, and a pot of money is assigned to each score value, divided among the applications with that value; below some score the amount is zero.  Applications are now "memoryless", meaning that the status and funding level of your last application have no bearing on your current application (I would argue this is bad for all kinds of reasons, but that's another discussion. See Ghoussoub's excellent blog for detailed summaries and a discussion of what's going on with NSERC.)

But the following details were interesting:

Let's get rid of Transactions letters (Updated)

Update August 11, 2011: According to an editorial in the August issue of Transactions on Wireless Communications (not yet available on IEEExplore), both Trans. Comm. and Trans. Wireless Comm. will stop accepting letter submissions as of September 1, 2011.  Original post follows.

Both the Transactions on Communications and Wireless Communications accept "letters". There are minor differences between the two journals, but letters are most commonly used as "enhancement of previously published work", i.e., minor results that fall short of a full paper. In both cases there are stringent length requirements: 10 double-spaced pages in the Transactions draft format excluding figures, which works out to about 4 pages in the two-column format.

Anyone who has written a journal paper -- or even a conference paper -- knows that 10 double-spaced pages is barely enough to say anything.  As both a reviewer and an author, I've seen the following dynamic happen over and over:

1. Author discovers an interesting little result. Not being quite enough for a paper, author writes a letter, leaving out details that s/he considers irrelevant to the overall point of the work, in order to meet the length requirement.
2. Reviewers are not satisfied with the level of detail in the paper. Ignoring scope and length requirements for letters, reviewers demand more detail, additional simulations, longer explanations, and so on.
3. Author adds the absolute minimum the reviewers demand, and then cuts, edits, shortens, and otherwise takes a butcher knife to the paper to meet the length requirement.
4. Go to 2.

"Letters" end up in a kind of limbo, delaying the review process and making nobody happy, even if the paper is eventually accepted. 

The problem seems to be that reviewers treat "letters" like regular papers. So why not make it official and drop the "letter" from the Transactions? Short papers could be handled just like regular papers, with the understanding that the magnitude of the paper's contribution should be proportional to its length. The Transactions on Information Theory did this years ago.

Papers at CWIT: PDFs and video

I posted earlier about my papers at CWIT.  I finally got around to uploading the PDFs and video.


J. P. K. Chu, A. W. Eckford, and R. S. Adve, “Distributed optimization of the Bhattacharyya parameter in wireless relay networks,” in Proc. 12th Canadian Workshop on Information Theory, Kelowna, BC, 2011. [PDF] (Video not available.)

L. Cui and A. W. Eckford, “The delay selector channel: Definition and capacity bounds,” in Proc. 12th Canadian Workshop on Information Theory, Kelowna, BC, 2011. [PDF]


Presentation video for the Cui/Eckford paper:

 

Jeffrey Simpson, do your research

Good news, everyone! Jeffrey Simpson has solved all that ails the university sector in Ontario: it turns out that those lazy professors need to stop doing their airy-fairy research and get their butts in front of the classroom.  Oh, and we also need heavy-handed government intervention to make this happen.

Simpson's column betrays an almost complete lack of understanding of the modern university, not to mention the role and importance of research.  I would invite Simpson to check the research page of any university in Ontario, listing high-profile and news-making results (e.g., U of T, York). Perhaps in his next column, Simpson can let us know which of these results he would trade against smaller class sizes for undergraduates, from the innovative and censorship-fighting Citizen Lab to the breakthroughs of the University Health Network to environment-saving advances in clean energy.  Or perhaps he can let us know which of the many innovative spin-off companies arising from university research Ontario can do without (at U of W alone, valued at nearly $1 billion annually in a 2001 report).

Simpson also fails to understand that there is no tension between research and teaching. Indeed, at the graduate level, research is teaching: graduate students learn the difficult process of developing new knowledge through research, under the close guidance of a supervising professor.  From personal experience, I can say that graduate supervision is a rewarding but time-consuming process; one that Simpson completely ignores.

I could go on, but I've got a lot of research work to do this afternoon! I'm working on an innovative communication technique for nanorobots that may one day revolutionize drug delivery and make invasive surgery obsolete -- take that, taxpayers! Meanwhile, before writing his next column, I suggest Simpson do a bit of the research he hates so much and acquaint himself with what universities actually do in 2011.

On Slepian-Wolf compression, in memory of Jack Wolf

Jack Keil Wolf, one of the giants of information theory, passed away last month.  His obituary was carried in the New York Times.

Wolf's signature contribution was in distributed data compression.  Say you're trying to retrieve two files, X and Y, from separate servers on a network. One strategy would be to compress both files individually to their entropy, H(X) and H(Y), and download them; this requires H(X)+H(Y) bits.  This is as good as you can do if X and Y are statistically independent.  However, if they are dependent, compressing X and Y together can be done at the joint entropy H(X,Y), which is less than H(X)+H(Y). But what can be done by the two servers, since neither has access to both X and Y?

Meeting of the minds

At CWIT in Kelowna, here are the only three Canadians to be president of the IEEE Information Theory Society.  From left to right: Professors Vijay Bhargava, Ian Blake, and Frank Kschischang.

Two papers at CWIT

I have two papers at this week's Canadian Workshop on Information Theory in Kelowna:

1. Lu Cui and Andrew W. Eckford, "The delay selector channel: Definition and capacity bounds"
Session: Coding and Information Theory I, Wednesday May 18, 9:00-10:40 AM

This is work from Lu's master's thesis [PDF]. The "delay selector channel" is a discrete-time channel model that captures some of the features of molecular communication with Brownian motion. The main contribution of this paper is a closed-form lower bound on the channel capacity.

2. Josephine P. K. Chu, Andrew W. Eckford, and Raviraj S. Adve, "Distributed optimization of the Bhattacharyya parameter in wireless relay networks"
Session: Relay Assisted Communication, Thursday May 19, 2:00-3:20 PM

This is work from Josephine's Ph.D. thesis. We give an iterative, distributed solution to the non-convex multi-source, multi-relay resource allocation problem, where the objective is to optimize the Bhattacharyya parameter for each source's transmission.


Paper PDFs will be posted shortly. I will be in Kelowna and presenting both papers.

A quick exercise on divergent sequences

I have a sequence and I'm trying to show that it converges.  Here's my attempt to turn a morning of frustration into a blog post.

Let s(j), j = 1, 2, ..., be a sequence of real numbers with the following properties:

• There exist constants a and b such that a <= s(j) <= b for all j.
• In the limit as j goes to infinity, s(j) - s(j-1) = 0.

Conjecture: Any sequence s(j) satisfying these properties is convergent.

Your job: Disprove the conjecture by providing a counterexample.

There are many possible answers, but I give one in the comments.

Seminar in Ottawa: Information-theoretic problems in molecular and nanoscale communication

I'll be in Ottawa this Thursday and Friday: Thursday I'll be the external examiner at the Ph.D. defense of one of Yongyi's students, and Friday I'll be giving a seminar on some of my recent molecular communication work. Details follow.

Time: Friday, April 29, 11 AM

Title: Information-theoretic problems in molecular and nanoscale communication

Abstract: Recent advances in MEMS/NEMS and systems biology have made it possible to manufacture customized nanoscale devices, such as swarms of nanorobots.  However, manufacturing is not enough: a significant remaining challenge is to solve the communication problem among these devices, which would allow them to coordinate their actions.  Furthermore, the nanoscale communication environment is rather different from the systems that are usually studied by information and communication theorists.  In this talk, I will introduce the nanoscale communication problem from an information-theoretic perspective, focusing on molecular communication, which mimics the way in which microorganisms communicate.  Mathematical models and achievable-rate results will be presented, and important open problems will be discussed.

A critic speaks

Personally, I have never been able to convince myself that the Metropolitan Opera broadcasts are cultural in any deep sense of the word. The broadcasting of ludicrous Nineteenth Century melodrama, accompanied by music which is emotionally powerful but frequently of staggering vulgarity, and projected by means of acting which often falls below the level of a high school literary society's play, is cultural only on a very special level. I am devoted to opera and never miss a performance if I can help it, but if I were going to broadcast something that was cultural, I would certainly not choose Lucia, La Traviata or Tosca.

Yours sincerely,
Robertson Davies

(I was a resident at Massey College during my Ph.D., where Davies was the founding master. [Source, via])

Paper at MoNaCom

I had a paper in the MoNaCom workshop, which was held on Sunday afternoon in Shanghai, in conjunction with Infocom 2011.  Satoshi presented the paper; unfortunately I had to miss what looked like a very interesting workshop.

In our earlier work on microchannel molecular communication, we noticed that naive placements of the transmitter and receiver were suboptimal.  However, when we tried to optimize these placements, we ran into a problem: our high-fidelity simulation of the molecular motors was computationally intensive, so it would have taken forever to run the huge number of simulations required in the optimization problem.  Addressing this problem, our paper gives a quick-to-simulate, though approximate, model for motor trajectories, and applies it as a design tool for optimizing information rates in microchannels.

N. Farsad, A. W. Eckford, S. Hiyama, and Y. Moritani, "A simple mathematical model for information rate of active transport molecular communication," in Proc. 1st IEEE International Workshop on Molecular and Nano-Scale Communications, Shanghai, China, 2011. [PDF]

Random matrices and the Kronecker product

The distribution of a zero-mean, jointly Gaussian column vector x is pretty basic stuff in probability: we get the covariance matrix R, given by

where the superscript T represents transposition. Then we find the probability density function (pdf)

where k is the number of elements in x.

But suppose you have not a random vector, but a jointly Gaussian, zero-mean k by k random matrix X. How do you express the pdf compactly? And can you compactly represent the pdf of matrix multiplications of X?

Is my salary any of your business? (Updated)

UPDATE: Doorey has an interesting take on the sunshine list.

For the first time, I made it onto Ontario's salary disclosure list.  I won't link to it, but a trivial amount of Googling would lead you to find out exactly what I earned last year.

On the one hand, my employer is a public institution, and I agree that the public deserves to know how their money is being spent.  And there are some individuals, like university presidents and senior executives of public corporations, whose compensation packages are large, and who negotiate their employment contracts individually; these packages should be on the public record.  But I'm a middle-ranked professor with no administrative authority, and my pay is set by collective bargaining. Do you need to know exactly how much I, personally, get paid?

The disclosure list would perform its function if it was published as it is today, but with names redacted:  the public would know, in general, how much professors and other civil servants get paid.  I don't see what extra public good is served by printing my name, which is a significant invasion of privacy.

And a memo to the local papers: "Many more public servants earning six figures" is not news, although it certainly provides inflammatory fodder for people who think public servants are all fat cats helping themselves at the public trough.  Salaries naturally go up as a result of cost-of-living increases, which track inflation, so it would be a huge surprise if the list did not grow.  A much better question, whether the size of the list is growing at the expected rate given inflation, is not answered by any of the media reports I read.

How engineers look at the world?

source: SMBC

The Tim Hortons School of Probability

Do you know what this object is? We've just come to the end of that late-winter Canadian ritual when we line up to buy coffee, hoping for the magic words: "Win donut / Gagnez un beigne".

There are a couple of neat posts here and here, using "roll up the rim" to illustrate the binomial distribution. But you can also use it to illustrate the geometric distribution.

The geometric distribution (GD) gives a distribution on the number of trials before the next win. It's like the binomial distribution (BD) for impatient people: The BD asks, "If I buy 20 coffees, how many prizes can I get?" while the GD asks, "How many coffees do I have to buy until I get my next prize?"

A quick update

I'll be liveblogging the India trip over here. (Written from Pearson, waiting for my flight to Frankfurt.)

A very short presentation on email etiquette

After receiving lots of questionable emails, today I gave a presentation on email etiquette to my first year class. I think they got the picture. Please feel free to use and/or modify it yourself.

PPT version, PDF version

Whirlwind Tour of India

A couple of months ago, I agreed to join a delegation to India from York's Faculty of Science and Engineering.  The idea is to make contact with Indian researchers, sign memoranda of understanding (MOUs) (e.g., covering graduate students and visiting faculty), and possibly to explore joint research projects through bilateral partnership programs.

We're going next week.  My schedule includes a day of meetings at the Bose Institute and University of Calcutta on the 24th; then off to Mumbai for meetings at TIFR on the 25th and IIT Bombay on the 26th, then off to Delhi that evening; a day off on the 27th (the plan is to visit the Taj Mahal); and then a workshop in Delhi from the 28th to the 2nd, with side visits to IIT Delhi and JNU. It'll be my first trip to India.

The trip is partially funded by a government agency. On the one hand, this is great: research is increasingly an international activity, but research funding remains annoyingly nationalistic.  In the absence of partnership programs like this one, it is almost impossible to construct international collaborative research teams, and breaking down those walls is a good thing.  On the other hand, it's surprising how eagerly universities are jumping at this money: we've been told this is "delegation season" in Inda; we're arriving shortly after another Canadian delegation, and we're being told which other universities have signed MOUs, hoping not to miss out on our chance.  You could argue this is symptomatic of general research underfunding in Canada; one wonders what Ghoussoub would have to say about it.

The blog is on hiatus for a bit, but I'll post about the trip when I get back.

How about a redesign?

Everybody's doing it, so why not me? Hopefully this will go down better than theirs.  I'll probably twiddle with the colors and so forth, but my main goal was to restrict the column width of the posts.

A famous communication theorist

I was reading a paper on MIMO recently, when I noticed that one of the authors was Maher Arar.  Surely it can't be that Maher Arar, I thought to myself. But in fact it is: here he is getting a PhD in EE from the University of Ottawa.

Congratulations, Dr. Arar! He even has a nice blog.

Pigeonholes and entropy, a work in progress

The pigeonhole principle is probably the simplest lemma in combinatorics:

• Say you want to sort k objects into n bins.  If n < k, then at least one bin must contain at least two objects.  

For example, a person can have only one of 366 possible birthdays (counting Feb 29).  By the pigeonhole principle, any gathering of 367 or more people must have people who share a birthday.

The lemma is obvious almost to the point of triviality, so it comes as a surprise that you can use it to prove powerful results; there are some examples in the book.

Lately I've been wondering whether it can be used to say anything interesting about entropy.  Here's the first thing I thought of: let X and Y be random variables on a discrete alphabet, and let S(X) and S(Y) represent the support of the probabilities of X and Y, respectively (i.e., x is in S(X) if and only if p(x) > 0). Then

• Theorem. If |S(X)| > |S(Y)|, then H(X|Y) > 0.
• Proof. By definition of entropy, H(X|Y) >= 0. If H(X|Y) = 0, then there must exist an injective map from S(X) --> S(Y).  However, since |S(X)| > |S(Y)|, no such map exists (by the pigeonhole principle).  Thus, H(X|Y) != 0, and the theorem follows.

 Not very exciting, I will admit.  I'm still thinking about it, any other ideas?

Bad web strategies: A short problem set

Question 1. Consider this tweet:

What is the target of the link?

a) The ComSoc blog.

b) A link to a screenshot of the ComSoc home page, highlighting the "Blog" button in the link bar.  The screenshot is part of a Facebook album, and clicking on the screenshot only navigates to the next picture in the album.  Being an image, text in the screenshot (including the blog URL) is not selectable for copy/paste.  From the link, there are no obvious ways to get to either the ComSoc home page or blog.  


Question 2. What is ComSoc's slogan?

a) "The world's leading membership organization for communications professionals"

b) "We have never heard of the internet before today"

What's a PhD worth at the finish line? On hiring committees

The blogosphere is roiling over the worth of a PhD.  Should PhD programs take all qualified students? Is the academic "meritocracy" a myth, i.e., are some PhDs more equal than others? Even an outlet as erudite as The Economist suggests doing a PhD might be a waste of time (the always-nameless correspondent calling her ecology PhD "pointless").

In all of these pieces, the worth of a PhD is measured by its convertibility into a tenure-track position. There's lots of ink to be spilled on this topic, and I don't have a grand, philosophical point to add about the worth of the PhD.  However, I'd like to talk about the "finish line" viewed by many PhD students: the hiring committee.

No, I don't want to "talk about" your exam

The college where I did my undergrad had the habit of printing your rank in your class along with your yearly grade report; the top student in each class got a small prize, usually a book. At the end of my third year, I was happy to read on my report that I ranked first out of thirty-something electrical engineers (it was a small college).

I left for the summer and returned for my senior year, but hadn't received my prize.  When I asked around, it turned out that the second-place finisher had complained to all our profs about his exam grades, and managed to get enough extra marks to take first place -- my book became his.

I realize it's a small, petty thing to remember after all these years.  But I think about it every time a student comes to my office wanting to "talk about" their mark on the final exam.