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Wireless gigabit alliance (WiGig) has a new(updated) website. For a first up, there is a link How WiGig Works which nicely explain what WiGig is all about, in a clear layman’s terms. If you ever wondered whether we saw the finale of the wireless rate surge, just re-think. We are still a lot far from drafting even a proposal, but there is surely plenty of light seen in the wireless horizon. As an example, HDTV would require about 3Gbps rate. WiGig is addressing applications such as this which demand rates beyond 3 giga bits per second. The brief tutorial is a compelling read.
The much expected Wolfram alpha has gone for a soft launch since last night. It had some start up glitches, as Wolfram briefed during the live demo, but nothing major fortunately, prevented me from getting a first feel of it. Erick Schonfeld has a nice blog with a detailed first hand feel description of this new computing web search engine. He also did a one to one comparison with Google for a few specific search queries.
My first impression is in much the same line as what I expected after reading Wolfram’s pre-launch blog. This is not a Google competitor for sure, but instead an incredibly complementing brother. Wolfram alpha is more of a scientific and quantitative information search engine. For instance, if you want to know the Taylor series expansion of exponential function 
wolfram1
This is the sort of query it likes the most and not something like “proof of Sanov’s theorem”. Google will incredibly list a set of documents which has the proof one is looking for, since it simply search down the web and display a listof matching queries, ordered based on pagerank, which is loosely speaking in the order of relevance.
Not all queries are bound to get a result with wolfram alpha, atleast for now. That is expected since it is not yet in launch mode, but on soft launch. In the coming days they are likely to have it running full fledged with all kind od queries supported.
So, the wolfram alpha is definitely going to be useful for very many cases and it surely is going to rock in scientific searches. I initially thought the Google squared which is going to come from Google shortly is addressing the very same segment of search area, but it is clearly different.
I tried “tallest mountain Switzerland” . It gave a very nice cute quantified table. I love this kind of result. It is also state things with less ambiguity. For instance the height is mentioned in meter, but there is a list of unit conversions listed along, which help people to map them into the units of their convenience.
I tried a query “Who is Claude Shannon”. This is what it displayed. Of course, the result you get is a very brief information about him. Same query in Google will lead you to the more detailed Wikipedia entry of Shannon or may be the Mathworld entry of Shannon among the list of hits . Wolfram alpha gives information more like in capsule form. If you need to know more, you should ask more. Clearly, what search engine to use is thus subject to the query type. I strongly see Google and Wolfram alpha are complementary. Wolfram alpha gives more or less one reply to a single question. Of course you can renew the query and then get answer to that. In some sense, this is like people asking questions to one another in real physical scenario. Imagine you ask a friend, knowledgeable pal that is: Who is Shannon? He would perhaps start answering in those lines as Wolfram Alpha do. On repeated question he will give more details. On the other hand, Googling is like broadcasting your query to a large pool of friends, each one of them sends what they know or heard about Claude Shannon. It is you,who decides whichamong the many answer(s)/explanation(s) suit your need!
We can afford some amount of spelling errors while entering the query in wolfram alpha. Since it is natural language based, that is a decent feature to have. I deliberately typed the query “distnace from Bangalore to geneva ” instead of “distance from Bangalore to geneva “. It understood the intended query and displayed the result in a nice quantified table. Eve the geographical trace between the two places is shown. Incredible!
When I tried “weather in Lausanne”, this is as good as it gets. Spot on with all possible things you want to know in one screen! It had a list of mountains and their heights mentioned!
In a nutshell, Wolfram alpha give you the best cooked food, given a user recipient as input. Google will give you a list of foods available and then you pick the one tasting suit . It really then is a question of preference, time, and satisfaction of the end user on what to choose from. As far as I am concerned, it is subjective. I see both of these are invaluable and both will co-exist. Scientists,economists, finance folks, mathematicians, historians are all bound to benefit from this new computing engine. I am waiting for a full release!
Today, I attended a very good talk given by Emo Welzl of ETHZ. I could not quite appreciate the drinks and snacks prior to the event, since the organizers kept too little of them and by the time I arrived, smart guys had grabbed hold of almost all of them. I had to content with a glass of orange juice! Anyway nothing comes free in this country. So getting an orange juice is itself luxury, one would say! Nevertheless, glad that I attended this talk. Monika Henzinger did the speaker introduction part, which she did very well. She mentioned that Emo comes from the same village as that of her husband (Thomas Henzinger). That is not really relevant, but I like such personal, less formal introductions. It takes the audience to a touch curious and close. He indeed proved her (Monika promised us that we are in game for a great talk) right with a truly nice lecture, calm, composed and thoughtful;words precisely chosen, well articulated throughout. He gave some insights into a problem which was never known to me. My field is not quite into SAT or algorithms, but at the end of this talk, I got to learn some thing. Moreover, he instigated me to learn a little more about these nice problems.
Here is a gist of what I understood. If you are interested in the talk subject, perhaps you should visit his homepage. What I state down is something my little brain, which never for once trained on this topic, digested out. Suppose we are given a Boolean function (that is a logic function which has either true or false, equivalently 0 or 1 results). Deciding satisfiability (known as SAT problem) of such formula in conjunctive normal form is known to be an NP complete problem. He discussed some nice (surprisingly simplified bounds) combinatorial bounds on the number of clauses (or equivalently constraints) for unsatisfiability. As usual in talks, I hardly could grasp the proof in total, but he began quoting the Lovász lemma as an essential ingredient. I got to learn a little bit about this rather nice and cute lemma. Loosely the lemma has the following setting.
If we consider a sequence of events 
I had earlier promised to update on the Xitip, when a windows setup is ready. Though delayed, I have something to say now. I have finally made a windows installer for the (Information theoretic inequality prover) Xitip software, which was working pretty smoothly on linux, cygwin and mac for a while. I was not too keen on making this windows installer since a few DLL files are involved with it. Besides it was a bit painful to include these nasty DLL files which would unnecessarily increase the bundle size. Some of these may not be required if Gtk is already installed on the machine, but anyway I made one double click style version to suit the layman windows users in information theory community.
Vaneet Aggarwal is the one who motivated me to make this up since he uses Windows. He showed some interest to use it, should a windows version be available. If atleast one user benefit from it, why not make it. In the process, I got to learn about an easy way to produce a windows install (setup maker) program. I used the freeware Install creator to produce it.
I will put this installer available at the xitip website, but for the time being you can access it from here. A lot of people suggested to revamp the xitip webpage which is pretty unclean at the moment. May be a short tutorial is impending. That will take a while; the next two and a half months are out of equation since I am pretty busy till then.
Todays IPG seminar had Fritz Eisenbrand (the Disctete Opt chair, Math department EPFL) talking about Diameter of Polyhedra:Limits of Abstraction. I don’t think I followed the topic too well, but this is a share of what I understood.
The topic is about a convex geometric problem on the diameter of a polyhedra. The question of whether the diameter of a polyhedron is polynomial or not seemed to be a longstanding open problem. The largest diameter 
The lower bound is due to Klee and Walkup and upper bound to Kalai and Kleitman. These bounds also hold good for combinatorial abstractions of the 1-skeleton of non-degenerate polyhedra (Polyhedron here is called non-degenrate). What Fritz and his colleagues have done is to look into the gap between these known lower and upper bounds. Apparently, the gap is wide and they have made some progress to get a super linear lower bound 
The way they showed this bound is by establishing the bound for the largest diemeter of a graph in a base abstraction family. Let us say, the abstraction family of connected graphs be denoted by 
I have not had a chance to see their paper yet. I must say, the proof was not all that within my grab during the talk. However it appeared that it is based on some layering and combinatorics. He said some applications to covering problem, in particular disjoint covering design which I didn’t follow that well. Sometimes I get the feeling that I am a little dumb to grasp these ideas during a talk. I wonder whether others understand it very well on a first shot presentation. I have put it in my agenda (among the millions of other papers to read) to see through this problem and proof, one day! His presentation was very clear and legible though.
I’ve finished reading the memoirs of Walter Rudin. It was a quick read for a few hours. His autobiography is titled The way I remember it, published by AMS in the history of mathematics series. It wasn’t particularly interesting, to say the least. From a mathematician who wrote excellent books on functional analysis and several others, I was expecting a much better story. Of course one cant write an imaginary story in an autobiography, but then the incidents in his life is pretty much the story of any European intellectual during the war days. The best I liked is the one from Karl Popper. However, I could connect many incidents from Rudin’s life, primarily because of the geography. There is a chapter on his days in Switzerland, which also touched upon Lausanne. That part for once enthused me! Was wondering how Lausanne would have been 70 years ago! If you are completely unaware of the life in Europe around the WW period, then this will give you a perspective. Like many scientific minds of that era, he had a long route to the United States. He discusses the path and family traits of that journey, in a somehat uncomplicated language.
In his autobiography, Rudin has discussed some of his contributions to mathematics as well. That part appeared a little informative, but technical read. If you know his work already, you would connect it nicely. I particularly liked the chapter on Function Theory in the Unit Ball of Cn.
In all, not a book I would recommend, unless you are a Walter Rudin fan and knows his contributions in much more detail. However, this may be a motivating read for a young school kid aspiring to be a mathematician. Why did I say that? I don’t know! Don’t ask me why either!
A very interesting report on the neuro socio development and progress of children from poorer background, is reported in the recent edition of The Economist. In the report they discuss the research study by Martha Farah of UPenn. Their investigation came out with a worrisome conclusion that, children born with poorer socio economic background have a greater chance of becoming underachievers (read as under performers compared to their middle-class counterparts). The study is of course based on statistical inference and hence there ought to be scope for exceptions (Large deviation theory!). However, being a statistical method, we can well assume that the behaviour is true on the average (expectation). This is truly not a conclusion we would like to hear, but to me, it appears to be a careful study and its conclusion opens up the ramifications of the larger crisis faced by millions of people all over the world, especially from developing countries and Africa.
What these researchers did is to study the stress level suffered by a person over the span of his/her life. They combined various type of pressure (such as systolic and diastolic blood pressure) and formed an index, what they called allostatic load. They found that this index is on the higher range among people from poorer background than those from middle class. They also have found that, the duration of the poverty life of a person is correlated with allostatic load.
The report appears to conclude that, stress is more or less the sole reason for spoiling the working memories of an individual. We could say that it is a little too strong a statement. Children under too much socio-economic stress tend to do badly in studies and that unfortunately carries on for ever. I am tempted to argue that, a socio-economic push, say by providing opportunities to such children will change the performance of an individual. After all, we know many instances of children born into poorer backgrounds scaled highs. But if you read the report carefully, they are not refuting this either. What they simply say is that, on a relative scale, the impact of stress during early childhood is much more serious than what we perceived to be. Children of poor perform poorly in school and stay on that way and sadly, remain as poor (under achievers) adults. Clearly, the authors refer ‘poor’ adults as state of ‘under achieving’ compared to their counter parts from a middle class background. In that case, one can always argue on the definition. True, one doesn’t have to be a genius to do well in life. But, the larger picture however is clear. A poorer childhood may limit his/her potential.
It can be very easily mistaken for that, this report is derived from a non scientific study. I too was inclined to think in those lines when I read the title. A careful reading however convinced me that, there could be genuine truth in their argument. After all, the conclusion is not on a single individual, but on a collection.
I am sure the wider picture of this report may have a scientific explanation too. Too much stress, at an earlier stage of life may prevent development of nerve cells. Bottom line is that, we simply do not want to take a risk. It isindeed very important that our children and future generations not to undergo that ill fate. We have a social responsibility to be aware of these and try to do a part to ease up the trouble, as much as we can.
A few years ago, during undergrad days, myself and friend Ramani during our lazy 75 paise mini canteen tea outing, were discussing a small riddle. It was motivated from a real world experience from our computer center in NIT Calicut (REC Calicut). In REC those days, we students almost exclusively used rubber slippers (Yes, those Paraqon brand which used to cost 20 rupees or so), usually called by the name ‘chappels’. With that, we were not only comfortable while walking and running around, but we’re equally at ease playing cricket and badminton with the very same foot support; and many other things too, including jogging. Those thin hard rubber slippers used to last an year or more without giving much trouble, other than perhaps an occasional tearing of the rubber tie. In all, we were at peace with that.
But there was an issue, not exclusively for this brand, but for chappals in general (shoes were a luxury of sort in the campus;atleast it wasnt very common). Not for everyone though! If and only if you were fancied of visiting the computer center! Well, computer center wasn’t all that fanciful then, since we were provided with only graphics less Unix terminals (no colour monitors!). You might wonder, huh! what age am I talking about? Besides, Internet and Emails were only taking shape then. Chats and browsing were not quite there yet;Unless you felt a touch inferior to the computer wizkid around, that was not a compelling centre de visite. As, ‘would be‘ electronics and communication engineers we had that occasional inferiority complex!. Computer center was air conditioned and was strictly slippers free. We were expected to keep our valuable slippers outside (no clock room luxury! well that was not a necessity either) before entering to that cooler room, filled with monochromatic terminals. Since most of the chappals dropped outside were alike (in size and also sometimes color) there was a good chance that at the time return, we ended up with a different pair of slippers (Some folks found happy for themselves by a visit to the computer center, just for a pair change, often to an improved lot!). Sometimes, we ended up having differently colored ones, say left foot white and right foot blue. That wasn’t a problem socially either, as long as you stayed within the campus. It was socially accepted within the walls!
Anyway, coming back to the riddle we were busy conjecturing on. We wanted to automate a clock room. The idea then would be to just deposit the chappals there at random. The clock room work automatically. Upon asking (at the time of return, say) it will select a pair at random and give it to you. Sorry, you cant have a choice. Just accept and hope for the best. We asked the questions:
1) What is the probability that everyone gets their own chappals
2) What is the probability that none of them get their submitted pairs
Assume 
We had thought and pondered about it for a while, then. In the end, we had found that the first one is easy, but the second one a little harder to generalize for beyond 
Now, it turns out that, the very same problem is akin to a well known problem in combinatorics. It is called the Hatcheck lady problem. It is fairly easy to solve it using the inclusion exclusion principle. The proof outline is shown below. As I type, memory fetches that discussion, sitting leg-folded on the cement bench at the REC mini-canteen, perhaps an occasional cool breeze around too.
The inclusion exclusion principle is the following:
The Hatchek lady problem can be stated with a similar story as the random clocker machine. (From Harris, Mossinghoff, Hirst’s book on Combinatorics and Graph Theory)
A lazy professor gives a quiz to a class of
For Hatcheck lady problem, the probability 
When
While the talk and boom about multimode multiband phone in CMOS is turning greener, there should be a natural question around it. How about doing all these in software? Rather add a level of programmability such that a great deal of issues from a hardwired implementation are shifted to more flexible firmware. Without contention, pros and cons with the idea of programmability still prevail. Clearly, one definite advantage I see with programmable design is the significant cost reduction and reuse. Additionally a migration or upgrade, which is imminent from a future gadget design point of view, can get done with relative ease with a programmable multimode chip. Building a suitable processor architecture to suit the modulations schemes (say an OFDM based scheme can have an inbuilt FFT engine or a WCDMA can have a correlator engine). Aren’t anyone working seriously in these directions? I am sure there are many, atleast startup ventures. Vaanu and Icera indeed are two things coming to my mind. How about the big boys? There were lot of furies about software programmable baseband chips being developed. Not quite sure what is the latest in that front. Isn’t it the next big thing in the offing? I am sure the EDA big houses have thought ahead for building tools for a heavily software oriented design, at least for years ahead. Or is it that, I am jumping the gun a little too far? However, I see some top level bottlenecks in making this programmable multimode chips realizable at an easier pace than a textbook concept. One of them is difficulty in getting away the analog front end. As a matter of fact, now I feel that, analog is going to stay.
So where are we heading to? Clearly, an all CMOS multiband multimode single chip (baseband and analog) with a near perfect RF and a software architecture would be the ultimate holy grail of cellular chip design. How many bands and how many modes to be incorporated becomes less important, if the programmability aspect is assured. Challenges within a single chip concept are themselves many. Clearly the RF portion is expected to take up lesser share of the overall chip size. An all digital front end is aimed in that direction. While a direct digitization of radio signal of high frequency eliminates analog life process significantly, there are several practical bottlenecks with this Utopian design model. We are not quite there to say good bye to analog entirely. Analog signal processing is still critical and inevitable, even for a programmable multimode dream. I will give you some numerical facts to substantiate my claim:
Suppose we decide to build programmable all digital zero if receiver for a 2GHz system (around the UMTS band). Then, Shannon Nyqusit sampling would demand at-least 4 G samples/second. Even with a processor which clocks 4Ghz and say 8 operations per cycle, our full steam purchase is going to be a maximum 32000000 operations per second. This theoretical figure is based on the assumption that processor memory is fully utilized. At the sampling rate of 4G samples/second, we only are going to get 
From this blog piece, I came to know that the smart MIT theoretical computer scientist Madhu Sudan is making a move from MIT to industry. He is set to take up a research position with Microsoft. At this economy troubled days, lesser mortals would take the conservative route that ensure stability and so on. They would say a move from a tenured professorship to a more volatile industry is risky. But then one of the smartest mind in the world can have a world revolve around him, if need be. So no surprises here. On the positive side it is a gain for industry, while it is a big loss for MIT, if Madhu decides to stay away from academia for too long.
Interestingly, on the very same blog, someone commented about other famous moves. Apparently, Venkatesan Guruswami, Madhu’s celebrated student is also making a permanent move from UWash to CMU. In industry, we are often associated with frequent hops. Academia is not too immune to attrition either. However, I see no harm in making smart moves. It is going to help the world, atleast in expectation.
As in EPFL too, there is imminent big fish attrition(s). Tom Henzinger and his wife Monika Henzinger are about to leave EPFL to take up a permanent position in Austria. The awesome twosome will be missed in EPFL.
Today, there appeared an interestng (and perhaps general) question posted on the Linkedin Analog RFmixed signal group. The question was this “Regarding multi-mode multiband RF transmitters for handsets (CMOS), what do you think are the hot issues (besides PA)?” I have given a short overview of the challenges that I could see when a multi mode phone is to be designed on CMOS: The phone has to support a wide range of frequency bands as well as multiple standards/technologies/modulation/air interface. Here is what I wrote. I am not sure whether the discussion is accessible to public. Hence I repost here.
Integrating the RF transmitter and receiver circuits is a challenging thing since we have to support multiple bands (within a single mode. Say GSM/EDGE should support GSM900 to 1900 bands) as well as support for multiple phone modes. For instance a natural multi mode multi band phone supporting GSM/GPRS/EDGE/WCDMA/LTE will have to consider a wide frequency ranges from 850MHz to over 2GHz. If we were to consider incorporating GPS and WLAN, add that extra consideration. Not just the transceiver circuitry, but also other components such as oscillators, filters, passive components, frequency synthesizers and power amplifiers. Another thing is that, for multi mode, the sensitivity requirements are much more stringent than a single mode, multi band design.
Since CMOS offers low cost, better performance and better scaling, to me that is the way forward. The natural choice of transceiver in CMOS would be the direct conversion/Zero IF, since it eliminates the costly SAW filters, and also reduce the number of on chip oscillators and mixers. Now, there would be several key design issues to be considered now with direct conversion architecture. Most notable ones are the well known ghost “DC offset” and the 1/f noise. Designers will have the task cut out to get a cleaner front end and as well as near ideal oscillators.
Now I see another problem with multi mode, depending on what level of flexibility we prefer on this integration. Do we need the phone to operate in multiple modes simultaneously? Say a voice call on GSM and at the same time a multimedia streaming on LTE. In such a case, the question of sharing components are completely ruled out. If not, say some components such as synthesizers and mixers (if in the same band for multiple modes) can be shared. Clearly, simultaneous mode operation will ask for increased silicon die size as well as cost. Challenges may be there for circuit isolation for different modes as well.
In all, depending on the level of sophistication (and of course all these things will have to be scaled economically too) the design,partitioning, architecture challenges are aplenty. Now the choice between a single chip (containing both analog baseband and digital baseband) versus two chips (analog and digital partitioned) will get a little more trickier with multiple modes. With multiple antennas (MIMO), add another dimension to this whole thing:-(.
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The latest edition of The Economist reported this shocking fact based on Amnesty international study on capital punishment: our civilized governments have executed close to 2400 people in the last one year alone; all in the form of capital punishment. Over 70% of these numbers are coming from China. Perhaps more revealing is the fact that Saudi Arabia and Iran took the percentage share (per population) when it comes to executing supreme order, all to its people.
Now, there may be a stronger story to defend these killings, because some of those criminals may indeed have done heinous crimes. But that, simply cannot justify capital punishment, Can it? To me, killing a human on any count is unjustified. By doing so, we are exhibiting more insanity. Why killing? We could rather put them in jail and let them be forced to work extra hard and learn the hardship of life.
The other day, couple of my Iranian friends and I were discussing about the sort of criminal law practiced in our respective countries (here India as in my case and Iran for them). One of them asked me about the kind of punishments that would be given for instance to a guy who accidentally injures someone on the road. I had to tell him, in India, a capital punishment is usually given only in rarest or rare crimes. Even then, there would be widespread opposition to the hanging. On the other hand, I was shocked to hear that in Iran, some crimes are dealt with a ‘blood for blood’ response. Apparently in Iran, for a recent case wherein a husband poured acid to permanently disable his wife’s eyes, the judge ruled a replica punishment so that the culprit get to feel the pain and agony that his victim had gone through. To me, this sounded too uncivilized a punishment, even though the victim deserve no mercy. He surely does not deserve rights for any decent public life for the heinous crime he carried out. The best way to punish such barbaric people is to put them through the most rigorous hardship over a prolonged period. That way, they get to experience the bitterness of life. Killing someone to compensate the loss of innocent people is simply no justification: At least I find no solace to accept it as a civilized way of dealing crime and criminals.
In a way, by killing the criminals we are giving an easy escape to those in-humans.
The latest talk/demo at TED opened up a fresh life to the possibility of a sixth sense. The MIT Media labs now have unveiled a prototype of the sixth sense setup. The whole thing is reasonably economical already and all indications are that this is going to rock some day. Incredible idea which went all the way to realization. Kudos to Pranav Mistry, Pattie Meas and their team. One thing I am really hoping out of it is that, this paving way to assist disabled people. For instance a blind, deaf or dumb person finding avenues to get a sixth sense aid would be really helpful.
http://www.ted.com/talks/pattie_maes_demos_the_sixth_sense.html
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