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I was playing a few tricks on a few centrality measures on a few graphs. SO, thought of penning down a quick piece of notes on the notion of centrality (A quick introduction can be found here along with Wikipiedia page on centrality)

Just heard from my EPFL folks that Mathematica 8 is just released. I am yet to get a chance to see it working, but I will look forward to it someday. I am quite happy with Mathematica7 already, but Wolfram always bring radical new stuffs which is special. In fact I am mighty pleased with version 7, but who knows what all new stuffs there in 8? I have been a huge fan of Mathematica since the early 2000, ever since Nandu (Nandakishore Santhi) introduced his new tool. tI use it pretty much for every computational mathematics job. These days, I even use it for plotting, much more than Matlab. Looks like there are a lot of new features added in 8. One of the claim from Wolfram is that, they added a lot of new stuffs on aids to work with (probability) distributions, which I think is going to help me a lot. One stellar new thing I notice (from the announcement) is linguistic argument support. Boy, that is hell a lot killer application. Forget the syntax then. If you want to plot a sin(x) with grid on, type just that sentence! That’s it! Rest Mathematica will do. Wow! Wow! How much is it for an upgrade? Or should I go for a trial? I can’t wait!

Recently (almost a month back), I happened to ask a simple question to an interview candidate. The candidate apparently worked, among other things, on the design of scrambler and descrambler blocks in 3G/LTE terminal development .Naturally, I expected him to know in and out of the block and of course the scrambling idea itself. To my innocence, the answer came: “Scrambling adds protection to the information source”. That was a bit of foot in the mouth reply, which I seldom expected from such a candidate profile. Anyway, come to think of it I shouldn’t overly blame the candidate because many a time, engineers overlook the primary goal of placing a block or unit in the overall design, even when they do a glory traverse with it. I personally think this is ignorance on part of an individual engineer if he or she doesn’t spend time to figure out the reasoning behind every single unit in  design, especially the one he or she works on, if not to an expert level, the intuitive idea gathering is paramount.

Anyway, let us get some facts right with scramblers. Scramblers are there in almost all the standardized data communication systems. It is some kind of randomize acting upon the information bit stream (Well, one can also think of it operating on non-binary symbol sequence or packets, but let us consider binary for the time being, for simplicity.). The input stream upon the act of a scrambler changes the patter of the original bit stream. Naturally, at the receiver should be doing a reverse operation (descrambler) to make sense of the source information. One can argue that, a receiver not having the right descrambler (descrambler is very well based on the scrambler algorithm) cannot retrieve the intended information, adding protection/security on the data stream is NOT the reason for the existence a scrambler/descrambler unit in a communication system. The why? Let us see why.

A typical receiver will have several algorithmic stages such as synchronization, equalization, decoding etc ( These are broad classifications. One can go into finer details. For the discussion on scrambling we can suffice with this much). All these stages are usually designed with the assumption that the source stream is  i.i.d (continuous stream of identically independent ‘0’s and ‘1’s). For example, a long stint of ‘0’s or ‘1’s can degrade the timing/clock synchronizer performance or may even result in loss of synchronization.

The other important argument on the scrambler is the spectral density (spectral mask as defined in standard documents) requirements, usually imposed by the standard specification and (country specific) regulation requirements.  Any periodicity (short or long), can result in spectral spikes, which in turn may result in co-channel and adjacent channel interference due to various nonlinear blocks present in the transceiver chain.

So, scrambler’s job is to make an uniform i.i.d stream so that, the spectrum stays as close to white. Similarly, the  receivers do not misbehave because of arbitrary source distribution.

Phew! Think of this. SAP in 2005 acquired a services company named TomorrowNow for $10 million. In just about 5 years, the new owner is in line to pay $1.3 billion to Oracle. For what? For all the wrong doing of the acquired company in their teens! There had been several corporate white collar crimes in the past. One distinctly vivid case is the Avant!-Cadence battle, but the new one scales much higher. Clearly, SAP wouldn’t have anticipated the literal realization of “tomorrow now” then, but now, it is a blown up penalty that SAP will have to content with.

So, what is the case against TomorrowNow (which is well part of SAP AG now)? Oracle filed a case against SAP for an illegal stealing/usage of Oracle licensed software. Oracle claims that TomorrowNow illegally copied software code needed to support customers without buying licenses (from Oracle) to access it. TomorrowNow made thousands of duplicates of copyrighted software obtained by illegally accessing electronic materials from Oracle’s customer-support websites, the lawyers said. That is quite a mess TomorrowNow brought into SAP. Well, now no go, but to pay the 1.3billion and work harder for future!

Some stomach upset over the last couple of days prompted me to switch off from any serious activity. To make matters worse, I injured my groin too. Anyway, that in a way forced me to read up a bit of news and contemporary stuffs. Two good articles came in my way.

Amazing article by Sainath, “Narcissism of the neurotic” Must read.
An eye opener on the Indian media:

I had written a few words already about many of the Indian media houses. One word suffices actually, “pathetic”. Now the latest expose is a formal confirmation. Bharkha Dut, Vir Sanghvi are taken off the cover.

Does anyone believe that the difference between the Lebesgue and Riemann integrals can have physical significance, and that whether, say, an airplane would or would not fly could depend on this difference? If such were claimed, I should not care to fly in that plane.

I recall hearing this interesting quote. If my memory is correct, I first heard it from Martin Vetterli, who either mentioned this during a talk/class or it was there in the footnote of his forthcoming book. It sounded funny that time, but I didn’t really know to whom this quote is originally attributed to. To my surprise, this has its origin dates to the story man Hamming. Well, why Hamming? Emre Telatar did tell me couple of funny stories about Hamming besides the one famous scream on the computers which eventually led to the discovery of error correcting codes! By the way, Emre is a walking encyclopedia when it comes to stories. He is a treasure in many ways!

Ok, coming back to where we started. Springer has published this nice conversation piece online for free. The title is “Mathematics and Design: Yes, But Will it Fly?”. It is not really a book, but a very interesting conversation discussing the above mentioned quote by Richard Hamming. The preface of the discussion itself couldn’t be more apt, which reads:

“Martin Davis and Matt Insall discuss a quote by Richard W. Hamming about the physical effect of Lebesgue and Riemann integrals and whether it made a difference whether one or the other was used, for example, in the design of an airplane. The gist of Hamming’s quote was that the fine points of mathematical analysis are not relevant to engineering considerations.”

A very fascinating read indeed. An even more fascinating, formal defense on Lebesgue’s right on why aeroplane fly is here. Well, the answer to aeroplane question: here is what Andrew Lewis has to say, “In the event that the reader is consulting this paper in a panic just prior to boarding an airplane, let us answer the question posed in the title of the paper. The answer is, “The question is meaningless as the distinctions between the Riemann and Lebesgue integrals do not, and should not be thought to, contribute to such worldly matters as aircraft design.” However, the salient point is that this is not a valid criticism of the Lebesgue integral.

A nice intuitive to way to explain what a Martingale is found here (Venkat’s Computational Probability course notes). Perhaps it was known already to many. To a layman, this is the best way to introduce Martingale, first up!

A sequence X_{1}^{n} =X_1,X_2,X_3,\ldots,X_n  is called a martingale if  \mathbb{E}\left[X_{k+1}|X_{k} \right]=X_{k}, for all 1< k <n. An intuitive way of thinking about martingales (and indeed the origins of martingales) is to imagine X_k as your total profit after the k th round of a gambling game. Then the martingale condition states that knowing your winnings in the first k games should not bias your winnings in the k+1th round. See the Wikipedia page for examples of martingales. The course notes is fabulous. I am following it on and off!

A superb goal from Messi in the friendly match between the South American football giants, Argentina and Brazil. Many have the same question:Can he do this magic again in Brazil in 2014?

Via Lance’s blog, I came across this hilarious prize known as Ig Nobel prize. The term “Ig” stands for “Ignoble”! The prize is apparently given to something which may appear to be funny, but has some serious reasoning behind. In other words, these are peculiar awards given to something  which”‘first make people laugh, and then make them think”. Quite amazing huh?

I am yet to explore a lot on this. Lance listed one very interesting one. I find it extremely noteworthy! Robert Faid of Greenville, South Carolina, farsighted and faithful seer of statistics, got the Ig Nobel prize for calculating the exact odds (710,609,175,188,282,000 to 1) that Mikhail Gorbachev is the Antichrist.I wonder how he arrived at this magical number! Didn’t Faid know how to play a game in the stock market then?

Wikipedia has an interesting entry on this topic. Would you believe, the young Russian physicist Andre Konstantinovich Geim who just won this years Physics Nobel for his work on graphene had also won the Ig Nobel in 2000! Quite amazing.

Just heard about the 2010 Hay festival was held last week in Thiruvananthapuram. Although I couldn’t have gone there, it felt nice to have had such a great global art and literary event in my own home state in India. The official website hosted some amazing scenes from various parts of Kerala, which to an ardent Kerala fan like me wished to see  all times. The Hay festival of arts and literature has become quite prominent in the public media, recently and what better place to have it, than the beautiful and literary rich Kerala!

Thanks to Youtube, I could gather glimpses from the event. Part of Vikram Seth‘s Storypooja is captured here. The one session, I would have liked to attend is Marcus du Sautoy on “The Number Mysteries: A Mathematical Odyssey Through Everyday Life“. I hope to see a video tape of this program online sometime soon! After all, Marcus claimed to have had a reason for everything, including why bend it like Beckam! Another of my favourite is ONV Kuruppu. His candid and lively talk is an anytime favorite of mine. He was supposed to have had a conversation with poet Sachidanandan. And, how much I missed Bob Geldof‘s conversation, let alone his concert!

D-day in another sport, that has a speed of its on. Sebastian Vettel is on pole, but all eyes are on Fernando Alonso, who will start third in Abu Dhabi. Can Mark Webber pull off a miracle from No. 5?

Thankfully, Michel Schumaker escaped unhurt from that freaking crash. Seeing it live, it appeared to be like a crazy head on. The last race of the season, the crash of this kind would have been a  massive sobermaker, but thankfully no major damages. The Imola crash is still looming large in memory and with Ayrton Senna’s nephew still racing, it just came back instantly, upon seeing the crash scene.

I remember this quote from George Orwell “if you want a vision of the future, imagine a boot stamping on a human face, forever”.

It is beyond comprehension to see that, we can do nothing on this. Think of this. Aung San Suki is detailed for 15 years of the last 20 years.

ABC mini clip

Sion Rain’s fabulous and touching song dedicated to Aung San Suki.

Through Mahdi’s Facebook feed, I bumped across this beautiful composition La Plage by the emerging (already emerged, I must say. Well critics may say, Mozart was already among pantheon of greats by 30!) French musician Yann Tiersen. The linked photo is even more stunning. Apparently this is a photo shot byPaul Patrick (titled “Girl in Gallery, Paris”).  Amazing shot! Just brought back memories. How beautiful it is to see kids in a free world!

Thought provoking start for a day!

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November 2010
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