Saturday, November 29, 2008

Mumbai Terror Attack

I am still in shock and utterly appalled by the terrible events in Mumbai. I can't imagine how someone can have so much anger, so much hatred, to gun down innocent people in such a pre-meditated and cold blooded manner.

I was first alerted to the unfolding horror late on Wednesday morning (Pacific time) when my sister sent me a short email:

Unprecedented terror in mumbai. Dileep is holed up in Intercontinental hotel but safe. Rest of us are at home.
I immediately switched over to to see what this was all about, and was horrified to read about the deadly saga that was unfolding. The areas under attack were exactly the areas I grew up in. We lived between the Taj and the Oberoi, both a short walk from our flat. And my school was close to Cama hospital and Metro cinema. And I've taken umpteen trains from VT station. Worse still, my sister lives right near where we grew up, now very close to this war zone.

My brother-in-law was out for dinner at the Intercontinental, just down the street from the Oberoi. When news of the attacks reached the Intercontinental, the staff immediately closed all entrances to the hotel. Thus no one could enter, but nor could any one leave. So my brother-in-law was stuck in the hotel. He went up to to the terrace of the hotel, and from this vantage point he could see the gun battle unfolding at the Oberoi and the fires burning at the Taj. Fortunately he was able to call my sister and assure her that he was safe. He spent the whole night at the hotel, finally reaching home at 7am.

I spent Wednesday constantly checking various news sources for updates. At about 6pm I was reading the update from the Times of India online edition when I happened upon this chilling line:

The chairman of Hindustan Unilever Harish Manwani and CEO of the company Nitin Paranjpe were among the guests trapped at the Oberoi.
Nitin and I are childhood buddies who grew up together in that very area. In fact, we were scheduled to meet next weekend. And now he was trapped in the Oberoi. I emailed some friends about his situation, but didn't get an update until later that night when my mother confirmed that he had been freed around 4:30am (India time). Apparently once the gunfire started, the staff quickly locked the doors to the room in which they were dining. And by God's grace the terrorists didn't try to enter.

My sister's close friend and mentor was visiting India from Singapore and he was staying at the Oberoi. When the attack started, he barricaded himself into his room and stayed there for the next 36 hours. My sister was constantly in touch with him via his Blackberry. Once again, by God's grace, the terrorists didn't get to him, and he was freed by the commandos once all the terrorists were killed.

I can't imagine the fear that Nitin and my sister's friend and all the others trapped in the hotels must have felt in those terrible hours. And what of the fear and anxiety felt by those close to the trapped people.

In the aftermath of this tragedy, there are more questions than answers. How many terrorists were there? 10 of them have been accounted for, but were there more and what are they up to now? Who really is behind these attacks? Is it the terrorist group Laskhkar-e-Taiba based in Pakistan? Certainly the sophisticated attack suggests significant military training. Was the Pakistani government complicit? Or, at least, did senior members of the Pakistani military or intelligence service unilaterally provide training and support to these terrorists?

And the most important question of all: what now? What should India do in response to these attacks? Certainly beefed up security is important---after all needing to fly in commandos from Delhi suggests a certain laxness that flies in the face of the risks. But does this mean that India, or at least the big cities, need to become police states with military personnel toting semi-automatic weapons visible everywhere you look? That would be a very sad outcome. But what's the right balance?

And what of Pakistan? Outright war with Pakistan would be very unfortunate as it would retard all the great economic progress that India has made. But going after the terrorist training camps in Pakistan seems essential. The best outcome would be if the Pakistan government, perhaps with appropriate pressure from the US government, sees that it is in Pakistan's best interest to help India in putting a stop to these terrorist training camps in Pakistan. Nicholas Kristof of the NY Times has a nice post on this.

I hope that the Indian government shows great strength and resolve in crafting a very effective response to this tragedy of 9/11 proportions.

Sunday, November 9, 2008

Significance of the Election

Much has been written over the last few days about the enormous significance of last Tuesday's election. Of all the pieces I've read, the one I enjoyed the most was a post by Judith Warner in her NY Times blog. In this she notes that despite the enormity of what just happened, it is difficult for our young children to truly appreciate what has been accomplished. She points to this wonderful photograph that ran in the Times that illustrates this beautifully:

In it, a black mother and daughter sit on the floor of a church in Harlem. The mother, Latrice Barnes, having heard of Obama’s victory, is doubled up in tears; her daughter, Jasmine, is reaching a tentative hand up to soothe her. To me, she looks like the future, reaching out to heal the past.
For me, this will be the enduring memory of election night 2008: One generation released its grief. The next looked up confusedly, eager to please and yet unable to comprehend just what the tears were about.

Sunday, October 19, 2008

California Propositions

You are all no doubt following the presidential race with avid interest and have already made up your minds as to who you're going to vote for! But you may not have focused yet on the rest of the ballot. If you vote in California, I am referring the bewildering array of propositions that we're going to have to weigh in on---a full dozen state-wide propositions and various local propositions. If you're wondering what to do with these state-wide propositions, this post is here to help. I've looked at the propositions and the recommendations of the LA Times and the SJ Mercury News to put together this post (complete with my recommendations). I'd love to hear your opinion on these recommendations. Also please do vote on Nov 4th---even if you think your vote won't matter in the presidential election, it could well matter for many of these important propositions.

Let's start with a summary of my recommendations:

Vote Yes on propositions 2, 3, 11, and 12. Vote No on all the rest.
(You may want to research proposition 1A a bit more, since that's the vote I'm least confident about. Also, the above are recommendations for the state-wide propositions. For the county and city propositions, I'm leaning toward voting Yes on Santa Clara County propositions A, B, C, and D and a definite Yes on Palo Alto proposition N.)

Now to the details of the propositions and the basis for these recommendations. A couple of guiding principles I used were the following. First, say No to unfunded mandates. It makes absolutely no sense to say that $X billion dollars must be spent on some cause (however wonderful) without saying where the money is going to come from. Second, say No to constitutional amendments unless you truly believe there's a constitutional principle at stake. As Patt Morrison notes in the LA Times, California makes it way too easy to add to its constitution: a simple majority of the voters who show up at the polls suffices. As a result there are almost 500 constitutional amendments, compared to only 27 amendments to the US Constitution. Don't add to this mess. Finally, if you're interested in the back story for each proposition, check out this article.

Here then are my recommendations and recommendations from the LA Times (LAT) and the SJ Mercury (SJM).
  • Proposition 1A: High-speed passenger train. Vote No on 1A.
    LAT: Yes on 1A. SJM: No recommendation yet.
    This is a difficult one. The goal is to build a bullet train connecting SF with LA and later expanding to Sacramento and San Diego. The basic SF-LA line is expected to cost $33 billion, with 75% of it raised from federal and private sources. This bond is to raise almost $10 billion. LAT articulates the promise of this high-tech bullet train: "A high-speed rail line would not only provide a cleaner and faster alternative to automobiles, it would encourage transit-friendly development." On the down side, LAT notes: "If voters approve Proposition 1a, it seems close to a lead-pipe cinch that the California High-Speed Rail Authority will ask for many billions more in the coming decades, and the Legislature will have to scrape up many millions of dollars in operating subsidies."

    I should be excited about the prospect of a bullet train in California. But I fear this is going to be just a sink of money that, at best, will result in a bullet train that won't be used effectively to make a difference. Nothing I've seen of public transportation in California gives me confidence that the government knows how to get it done effectively. I think of San Jose's Light Rail as an example of a pretty ineffective form of public transportation. And so while I would love to be proven wrong, I have to recommend a No vote here. Read the LAT Yes case and make up your own mind.

  • Proposition 2: Prevention of Farm Animal Cruelty. Vote Yes on 2.
    LAT: No on 2. SJM: Yes on 2.
    This proposition is all about the treatment of egg laying hens (pig and veal farming is small in California). Egg laying hens are treated quite inhumanely, being confined to cages the size of a sheet of letter paper. While LAT agrees that this is inhumane, the No argument is that this proposition won't have the intended effect---it will only serve to make California eggs expensive thus driving the industry out of California. The inhumane treatment would then be meted out in neighboring states on in Mexico. SJM responds that the extra cost isn't expected to be that high, that there's plenty of time for farmers to adapt, and that the growing demand for cage-free eggs will give California a competitive advantage in the future. My own feeling is that treating these hens more humanely is the right thing to do, so this proposition deserves your support.

  • Proposition 3: Children's Hospital Bond Act. Vote Yes on 3.
    LAT: Yes on 3. SJM: Yes on 3.
    Authorizes nearly $1 billion dollars in bonds to expand and upgrade California's 8 regional and 5 UC children's hospitals (including Lucille Packard, UCSF, and Oakland Children's here in the Bay Area). This seems like a critical need. As SJM notes: "Children's hospitals throughout the state are overflowing with the seriously ill and injured. ... At Stanford, Lucile Packard Children's Hospital is forced to turn away more than 400 children every year." And LAT notes that Medi-Cal rates are so low that these hospitals can barely pay for operating expenses with nothing left over for capital expenses. This is money well spent.

  • Proposition 4: Waiting period and parental notification before termination of minor's pregnancy. Vote No on 4.
    LAT: No on 4. SJM: No on 4.
    Both LAT and SJM give compelling opinions on why this constitutional amendment is deceptive. For example, SJM says: "From top to bottom, Proposition 4 is the most deceptive measure on the California ballot this fall. It might look like yet another well-meaning but misguided effort - the third in four years - to force minors to notify their parents before seeking an abortion. But this year's version is more insidious. Voters should run to the polls in November to reject it." Read both opinions before you even consider voting yes. Also check out this piece by Francesca Ratner.

  • Proposition 5: Non-violent offender rehabilitation act. Vote No on 5.
    LAT: No on 5. SJM: No on 5.
    On the surface this looks like a proposition worth supporting: non-violent drug addicts using crime to feed their additiction would get rehab instead of jail, thus saving money for jails. But in fact, it's full of loop holes and would unleash complete chaos. The Con case in the voter guide says that "Loophole allows defendants accused of child abuse, domestic violence, vehicular manslaughter and other crimes to effectively escape prosecution" (presumably by saying that "drugs made me do it"). LAT strongly agrees with this: "If it passes, Californians would soon learn that they had swept away the state's few successful diversion programs, inflicted chaos on the parole system, layered on a staggering new bureaucracy and set back the cause of modernizing drug treatment."

  • Proposition 6: Save neighborhoods act. Vote No on 6.
    LAT: No on 6. SJM: No on 6.
    This is one of those unfunded mandates: requires almost $1 billion extra for law enforcement without identifying a source of funds. It also mandates 30 revisions to California's criminal laws (not clear these are needed), adds new bureaucracy, and builds in a provision that amending it requires 75% of the legislature (the recent budget battle only required 2/3rds of the legislature, and we saw how that went). As SJM notes: "Initiatives like this have distorted state priorities and tied up the budget in knots."

  • Proposition 7: Solar and clean energy act. Vote No on 7.
    LAT: No on 7. SJM: No on 7.
    Requires utilities to increase electricity generation from renewable sources. Sounds good, doesn't it? But turns out everyone opposes it: major environmental groups, major utilities, renewable energy providers, consumer groups, taxpayers association, unions, both political parties---they all oppose it! Read the op-eds to see all the things wrong with this proposition. And don't feel that a no vote means less renewable energy. LAT notes: "Under a law passed two years ago, the state is on a path to cut its greenhouse gas emissions to 1990 levels by 2020. There's broad agreement among policy-makers, including Gov. Arnold Schwarzenegger, that in order to reach this goal, the state must get 33% of its power from renewable sources by 2020." So it's going to happen without this proposition.

  • Proposition 8: California marriage protection act. Vote No on 8.
    LAT: No on 8. SJM: No on 8.
    This is a constitutional amendment that eliminates the right of same-sex couples to marry. Do you really want your constitution eliminating rights rather than granting rights? LAT, in its strongly argued piece, says: "We fervently hope that voters, whatever their personal or religious convictions, will shudder at such a step and vote no on Proposition 8." Proposition 22, passed in 2000, also eliminated same-sex marriage, but it was overturned by the California Supreme Court as being unconstitutional (thus the constitutional amendment here). LAT notes that: "Californians have accused the state Supreme Court of obstructing the people's will on marriage before -- in 1948, when it struck down a ban on interracial marriages."

  • Proposition 9: Victims bill of rights act. Vote No on 9.
    LAT: No on 9. SJM: No on 9.
    This is one more of the constitutional amendments that duplicates many rights that victims already have in the law and adds many others. It is a naive attempt to protect victims, but only serves to provide them new and inappropriate roles in prosecution. LAT notes: "The level of punishment a criminal receives should not depend on how persistent a particular family is in pleading for punishment or blocking parole. Civilized justice rejects vendetta and instead places retribution in the hands of the entire society. It may seem depersonalizing, but that's a goal, not a defect, of our system."

  • Proposition 10: Renewable energy and clean alternative fuel act. Vote No on 10.
    LAT: No on 10. SJM: No on 10.
    Authorizes bonds worth $5 billion to fund various clean energy initiatives. But a bulk of this money, some $2.875 billion worth, is reserved for alternative fuel vehicles with most of it going to vehicles using natural gas rather than for things like plug-in hybrids. That's not surprising since this proposition is sponsored by Texas billionaire T. Boone Pickens who co-founded Clean Energy Fuels Corp. that operates natural gas filling stations. There are lots of other problems with this proposition (see LAT and SJM for details). A much better way to get to the goal of more clean energy is to mandate vehicle pollution limits (which the Bush adminstration prevented California from enacting).

  • Proposition 11: Redistricting constitutional amendment and statute. Vote Yes on 11.
    LAT: Yes on 11. SJM: Yes on 11.
    Here's a constitutional amendment that is worth supporting, and it does feel like a constitutional issue. It puts the power of redistricting for state elections (though not Congress) in the hands of a 14 member commission rather than in the hands of the State Legislature. In the current situation, LAT observes that: "Voters are supposed to choose their representatives, but in California, political parties select their voters." SJM notes that: "Proposition 11 would deny incumbents the ability to use redistricting to their advantage. ... Legislators put self-interest first when they control redistricting. Minorities and everyone else will benefit from taking that power out of their hands."

    This is a case where I've changed my mind! In a past election I recommended voting against a similar proposition. This was at the height of the Bush era when Texas was using redistricting to cement Republican control, and I didn't want the Democratic party to be at an unfair disadvantage in California. This view was perhaps short-sighted, and LAT addresses it squarely: "By the same token, it would be foolish for Democrats to oppose the measure out of a belief that it would cost their party its majority in Sacramento. It won't. For every district it puts in play that currently elects Democrats, it is just as likely to put in play a district that currently elects Republicans. It would simply ensure that legislative Democrats (and Republicans) would heed voters and not just party bosses."

  • Proposition 12: California veterans bond. Vote Yes on 12.
    LAT: Yes on 12. SJM: Yes on 12.
    This is the most straightforward Yes vote. It provides a $900 million bond for farm and home aid for California veterans. The aid is in the form of loans to veterans, so historically it has not cost the state anything. Californians have approved this 26 times before, and there's no reason why we shouldn't support our veterans again this time. And what ever you may think about the war in Iraq, supporting veterans is a no-brainer.

Sunday, September 14, 2008

Vipassana Meditation

Vipassana is a meditation technique originally taught by the Buddha. It is meant to promote peace and harmony in ones life and eliminate the agitation, irritation, and disharmony one often experiences. The link above provides a summary of the principles underlying the technique. These principles are discussed at greater length in the book The Art of Living (note: this is unrelated to the Art of Living courses one hears about). The technique itself is taught in a completely free 10 day course held at various locations around the world (see the Vipassana site for details of a course near you).

I was introduced to Vipassana by my father. He has been practicing Vipassana for over 15 years now. My father is the most spiritual person I know---not religious in a traditional sense, but rather someone who was always searching for the higher truth. He says that of all the things he's learnt, Vipassana has been by far the most beneficial. This is high praise indeed.

I've read The Art of Living and have heard a series of lectures by S. N. Goenka, the person who has been instrumental in spreading Vipassana in India and around the world. From everything I've read and heard, the technique sounds very compelling. There's no hocus-pocus. It's a very concrete technique, with very concrete reasons for why it works. I'm not going to try to distill the essence of the technique here; for that I refer you to the above sources for an authoritative and comprehensive treatment (but I'm happy to talk to you about my understanding if you're interested).

An important point, emphasized by Goenka, is that reading books or listening to lectures is no substitute for actually practicing Vipassana. A good friend of mine, Raj, recently had the good fortune of actually attending a Vipassana course. Here's what he writes about his experience:

Just got back from Vipassana. 11 days of living like a monk in silent meditation. It is wilderness survival training for your mind. Training your mind to survive on its own and manage your anxieties, fears and other strong emotions without the support of conversation, reading, television or any contact with the outside world. You learn how to control your subconscious mind to recognize and control your cravings, desires and attachments. It is frightening to realize the depth and strength of the roots of your cravings. As you try to teach your subconscious mind to be equanimous to cravings, these deep rooted desires literally surface in waves that get amplified as they bounce around in your head without any of the usual distractions to dampen their intensity. Your mind feels like it is going to snap, much like the suspension bridge bearing the army garrison that did not break file. The first few nights I literally woke up sweating in my eight by eight cell surrounded by the ghosts of physical manifestations of my cravings swimming around me in the darkness. It starts getting better after about the fourth day.

That sounds like a pretty intense experience! (And, yes, he's a rather good writer!) I've been wanting to do the course for some time now. I almost attended a course back in 2004, but a minor emergency at the last minute intervened and I chose not to attend. Now, almost 4 years later, I'm finally getting around to fixing this omission : I'll be attending a course starting next week (assuming, of course, there are no emergencies this time!).

Friday, September 12, 2008

Google's Search UI

I wanted to make a note of a couple more Google blog posts that point at some more cool technology. No, I'm not talking about Chrome or the Chrome comic book. Rather, I'm referring to two recent posts by Ben Gomes. In the first post, Ben talks about the principles that guide the design and evolution of the Google search user interface. Of course, any talk of the evolution of the search interface raises a natural question:

A common reaction from friends when I say that I now work on Google's search user interface is "What do you do? It never changes." Then they look at me suspiciously and tell me not to mess with a good thing. Google is fine just the way it is -- a plain, fast, simple web page. That's great, but how hard can that be?"

Turns out it's not as easy as it may seem. Ben discusses a number of principles that guide UI development and provides several examples of the principles in action. One of the most interesting points he makes is related to the goal of search: get you to the web pages you want as quickly as possible. ... This goal may seem obvious, but it makes a search engine radically different from most other sites on the web, which measure their success by how long their users stay. We measure our web search success partly by how quickly you leave (happily, we hope!).

A key part of UI development is experimentation on live traffic. In his second post, Ben describes a series of UI experiments ranging from big, prominent changes to tiny, subtle ones.

... we test almost everything, even things that you would think are so small that we could not possibly care (nor could they possibly matter). In fact, small changes do matter, and we do care.

Check out these posts for a glimpse of the care with which the Google search UI is designed.

Saturday, August 23, 2008

Olympic Track

So after a wonderful week of Olympic swimming, we had a very fun week of Olympic track! The star of the week was, of course, Usain "Lightning" Bolt of Jamaica---3 gold medals with 3 world records. How do you start celebrating with 15 meters to go in the 100 meters and yet break the world? And how do you break Michael Johnson's seemingly unbreakable 200 meter world record while running into a stiff 0.9 m/s headwind? And how do you do all this while clowning around before every race? A completely remarkable young man!

There were lots of other great events. One of my favorites was the the mens 10000 meter. Ethiopia's Kenenisa Bekele was the star coming into the event. Two Eritreans and two Kenyans wanted to take Bekele out of the race, and so they tried to break away from the pack at various points in the race. But Bekele just hung in there right behind the leaders, usually in third place, sometimes falling back to fourth place. And then, with one lap to go, Bekele decided that he'd had enough---he went into overdrive with his famous finishing kick and left the field in the dust. He ran the final lap in something like 54 or 56 seconds---and that's at the end of 10k race! Quite a remarkable effort.

The high hurdles were exciting in both the mens and the womens events. Dayron Robles of Cuba won the mens 110 meter hurdles in convincing style, with exquisitely beautiful hurdling! (On a side note, it was a little confusing to see some who looked so nerdy hurdle so beautifully...:-) In the women's 100 meters Lolo Jones, the favorite, took control of the race and was all set to win in style, when tragedy struck---she hit the 9th hurdle causing her to slow down and helplessly watch as most of the rest of the field swept by her. Her loss was reminiscent of Gail Devers's fall at the end of the 100 meter hurdles in Barcelona.

Another favorite to lose was Sanya Richards in the women's 400 meters. She entered the home straight leading comfortably, looking like she had the race all sewn up. But suddenly things started going wrong and she couldn't find the extra gear necessary to finish, and so had to watch helplessly as Britain's Christine Ohuruogu and Jamaica's Shericka Williams powered past her.

And another highlight (or, more appropriately, a lowlight) was the butterfingers displayed by both the US mens and womens 4x100 meter relay teams. In the semi-finals, both teams were leading as they entered the final exchange, only to drop the baton in truly tragic style. It's unclear whether either team would have challenged the powerful Jamaican teams in the finals, but now we'll never know. (The Jamaican women had their own butterfingers in the finals.)

Finally, Yelena Isinbayeva of Russia turned in a typically dominating performance in the women's pole vault to win gold and break the world record. This is the 15th time she's broken the world record, reminiscent of her countryman Sergey Bubka who broke the pole vault record 17 times!

All in all, a very fun week of track (though I think I enjoyed the week of swimming more).

Sunday, August 17, 2008

Olympic Swimming

That was an incredibly fun week of Olympics competition! For us it was mostly about the exciting swimming events (and a little about gymnastics). Naturally, the biggest news in swimming (and of the Olympics thus far) was Michael Phelps's eight gold medals. But the most dramatic and exciting moment of the week belonged to Jason Lezak in the anchor leg of the 4x100 meter freestyle relay: how do you spot the world champion (France's Alain Bernard) almost a body length lead and then find some hidden strength to close the gap in the last 25 meters and out-touch Bernard by eight one-hundredth of a second?! Of course, Phelps's victory in the 100 fly was even closer---by powering to the finish with a half stroke he out-touched Serbia's Cavic (who was gliding to the finish) by the smallest possible margin (one one-hundredth of a second)!

There were plenty of other exciting races. In the womens 400 meter individual medley Katie Hoff, the reigning world record holder, led much of way and appeared to have a stranglehold on the race. But Stephanie Rice of Australia tracked her down and passed her toward the end to win gold. In the 200 meter breast stroke, Rebecca Soni caught up with and passed Australia's powerful Liesel Jones. Soni looked strong and smooth at the finish, while Jones had started faltering on the final 50. And, best of all, Dara Torres won a silver for all us middle-aged geezers! Unfortunately, she wasn't as lucky as Phelps---she lost the gold by one one-hundredth of a second.

All in all, a great week of swimming!

Saturday, July 26, 2008

Truth or Fiction?

As you know, we are big fans of Jack Bauer and the show 24. This in spite of the fact that Bauer and his cohorts regularly use torture as a standard interrogation procedure. (Not only is it terrible, we also know torture doesn't work well as an interrogation technique.) But we take this in stride and ignore it---it is after all fiction. And escapist fiction at that. Right?

Apparently not...

A recent NY Times op-ed by Bob Herbert talks about a new book called The Dark Side: The Inside Story of How the War on Terror Turned Into a War on American Ideals by Jane Mayer of The New Yorker. It spends a lot of time on David Addington, a key member of Cheney's staff:

In the view of Mr. Addington and his acolytes, anything and everything that the president authorized in the fight against terror — regardless of what the Constitution or Congress or the Geneva Conventions might say — was all right. That included torture, rendition, warrantless wiretapping, the suspension of habeas corpus, you name it.

Okay, fine---this isn't particularly surprising. But here's what really got me:

To get a sense of the heights of madness scaled in this anything-goes atmosphere, consider a brainstorming meeting held by military officials at Guantánamo. Ms. Mayer said the meeting was called to come up with ways to crack through the resistance of detainees.

“One source of ideas,” she wrote, “was the popular television show ‘24.’ On that show as Ms. Mayer noted, “torture always worked. It saved America on a weekly basis.”

What??? They were really looking to 24 for ideas on what to do to the detainees?

Friday, July 18, 2008

Ranking Technology at Google

In a previous post I mentioned that Amit Singhal had promised to have a follow-up post focusing on the technology underlying Google's search algorithms. Earlier this week Amit delivered on his promise with a fine post entitled Technologies behind Google ranking. He says that the driving force underlying ranking is to give users what they want:

Search in the last decade has moved from give me what I said to give me what I want. User expectations from search have rightly increased. We work hard to fulfill the expectations of each and every user, and to do that we need to better understand the pages, the queries, and our users.

Check out the post for more detail.

Friday, July 11, 2008

Chocolate Chip Cookies

I'll admit it---I have a sweet tooth. I love desserts of all sorts, ranging from western desserts like Prolific Oven's divine Swedish Princess Cake to Ben and Jerry's ice-cream to Indian desserts like rasmalai and gulab jamun. But above them all is the humble chocolate chip cookie, served warm with soft melt-in-your-mouth chocolate chips! It's a dessert I have a very hard time resisting.

So you can imagine that I was quite thrilled to read this recent article in the NY Times entitled Perfection? Hint: It's Warm and Has a Secret. It's all about baking the perfect chocolate chip cookie, complete with a recipe. The author talks to a number of bakers to get the recipe. But why talk to bakers when:

... almost everybody say[s] they prefer homemade to bakery bought?

Mr. Rubin smiled, having already figured out the answer. “It’s the Warm Rule,” he said. “Even a bad cookie straight from the oven has its appeal.”

I certainly subscribe to this view. But there's more to it than serving it warm. Mr. Rubin provides two secrets to baking the perfect chocolate chip cookie:

First, he said, he lets the dough rest for 36 hours before baking.

It seems this allows

... the dough and other ingredients to fully soak up the liquid ... which bakes to a better consistency.

The second secret is apparently to bake large cookies. The reasons for this are more complex and worth reading, at least for a laugh; not unlike the description of a fine wine (that claims to have hints of things that I can never sense), it involves phrases such as "flavor similar to penuche fudge" (what the hell is penuche fudge any way?!).

Nonetheless, it all sounds very exciting. I'm going to try the recipe one of these days and I'll report back on whether it lived up to the billing. (And maybe I'll figure out what penuche fudge is like!)

Thursday, July 10, 2008

Technology at Google

There's been a recent flurry of interesting blog posts describing different pieces of technology at Google. Udi Manber introduced the work of the Search Quality group at Google (I work in this group). His post is the first in a series of more in-depth posts. Here's my favorite bit in Udi's post:

...but the goal is always the same: improve the user experience. This is not the main goal, it is the only goal.

Amit Singhal followed up on Udi's post with a discussion of the philosophy underlying Google's ranking algorithm (Amit has promised a follow-up focused on technology). Here's how Amit describes our philosophy:
1) Best locally relevant results served globally.
2) Keep it simple.
3) No manual intervention.
In a separate series of posts on how data is used within Search Quality, Paul Haahr and Steve Baker write about using data to build language models. They observe that:

By analyzing how people use language, we build models that enable us to interpret searches better, offer spelling corrections, understand when alternative forms of words are needed, offer language translation, and even suggest when searching in another language is appropriate.

Matt Cutts follows up with a post on using data to fight web spam. He says:

Our logs data helps ensure that Google detects and has a chance to counteract new spam trends before it lowers the quality of your search experience.

Outside of Search Quality, I'm particularly pleased about the recent announcement to open source protocol buffers---our data interchange format. Protocol buffers are pervasive inside Google and are a very effective way of encoding "...almost any sort of structured information which needs to be passed across the network or stored on disk. "

Two other announcements are also worth highlighting: Google's C++ testing framework and Google's C++ style guide have both been open sourced.

Finally, here's a video of the Google Factory Tour of Search held back in May.

I have a short segment in there (at about the 65 minute mark) describing some of the work our group has done on query understanding. Earlier in the video (at about the 56 minute mark) Trystan Upstill talks about our group's work on International Search Quality (which is Amit's first point---best locally relevant results served globally). And earlier still (at about the 46 minute mark) Johanna Wright talks about Universal Search.

Wednesday, July 9, 2008

Vegetable Harvest

I wrote earlier about growing vegetables in EarthBoxes. After I had finished the planting, Mala made the comment that she hoped we'd have at least one meal to show for the effort and expense... I'm happy to report we've hard our first harvest! Our kids were very excited to harvest beans and basil for a dinner we were preparing for some guests. Here's what they got:

On the left is some basil to serve as a garnish on a pasta dish, and on the right some beans which we steamed as a side dish. Within a week we had a second harvest:

Lots more basil---this time to make some delicious pesto---and more beans. (The kids brought in some oranges from our orange tree, but the tree hasn't really been taken care of and the oranges aren't very good.)

And today, less than a week later, we got another round of beans. The tomatoes are also beginning to show up---there are already more than a half dozen small green tomatoes and lots of flowers. The bell peppers are only just starting out---they're really tiny at this point---and the serrano pepper is still holding out and only now seems to have started flowering. All in all things appear to be going quite well. While we're not exactly "self sufficient", I think we've crossed the rather low bar Mala set!

Sunday, June 22, 2008

Identity theft protection

You have no doubt heard LifeLock's ad on the radio. It's where the CEO of LifeLock says: "My name is Todd Davis. My social security number is xxx-xx-xxxx" (he actually provides his real social security number in this ad, and you can also find it on LifeLock's home page). The point of the ad is that LifeLock protects you from identify theft, and Mr. Davis is so confident of their service that he is quite comfortable publicly sharing his social security number. When I first heard the ad, it definitely piqued my curiousity.

So how does this service work and, more importantly, is it effective? Not surprisingly, there's been a lot of controversy in the news about whether or not it works. Bruce Schneier has a great post on the controversy and how LifeLock works. The controversy really stems from the core of what LifeLock does: they put fraud alerts on your credit reports from the three major credit reporting agencies, forcing lenders to verify your identity before they can issue credit cards in your name. Lenders and the credit reporting agencies hate this (it makes it harder to give credit), and so they've started a smear campaign against LifeLock (thus the controversy). In addition to the fraud alerts, LifeLock apparently does a bunch of other clever things to limit your exposure to identify theft.

So is this a service you should run out and sign up for? Probably note. Schneier notes: "At $120 a year, it's just not worth it." It's unlikely you'll be a victim of identity theft. And even if you are, it has become relatively easy to clean up the mess. Furthermore: "... it's hard to get any data on how effective LifeLock really is."

And the best part is: " can do most of what these companies do yourself." The second link (from the blog at is particularly useful. They provide a series of relatively easy steps you can take to protect yourself from identity theft. One key step is to regularly monitor your credit reports. And here's what they say about doing that for free:

You are entitled to one free credit report per year from each of the three major credit reporting agencies, Experian, TransUnion, and Equifax. You get these reports through Only use this site. Others that sound similar require you to pay.

The important point here is that you should go to for your free credit reports---don't sign up for any other service that's going to charge you for this free service.

Sunday, June 15, 2008


I just saw Tiger Woods birdie the 72nd hole at the US Open to force an 18 hole playoff tomorrow with Rocco Mediate! And this after his tee shot went in the bunker, his bunker shot landed in the rough, and the shot from the rough landed on the green but required a long putt. And he made it! Amazing! The man has nerves of steel!

Monday, June 9, 2008


Ever since we saw the Bristlebot created by Evil Mad Scientist Laboratories, the kids and I have been wanting to build our own! It's taken us a few months to get to it, but last weekend we finally did it! Here it is for your viewing pleasure:

We basically followed the instructions provided in the original. A few things of note:
  • You can get the pager motor out of an old cell phone. I tried doing that, but I didn't have the right kind of small screw driver, and I found it hard to open up the cell phone. So instead I went to and bought a few 7mm Namiki pager motors.

  • The pager motors I bought come with leads attached, so there was no need for any soldering. You simply place one lead under the battery, with the lead and the battery stuck to the foam tape. We attached a piece of tape to the other lead and stuck it to the top of the battery to start the motor running. The tape at the top worked nicely as a switch: simply pull off the tape to stop the motor.

  • Make sure that the back of your toothbrush is smooth. Some of the newer Crest toothbrushes have raised patterns on the back, and the foam tape doesn't stick properly to it.
All in all a really fun little project that, once you get all the parts, can be completed in less than 10 minutes!

Wednesday, June 4, 2008


I knew of Ubuntu as a Linux distribution, but I didn't know what the word meant. Then this morning, while I was belting out a 45 minute run at they gym, I heard on TV that the Boston Celtics break their huddle with a shout of "Ubuntu!". It seems Ubuntu roughly means "I am what I am because of who we are".

Wikipedia tells us that it is a Bantu word describing " ethic or humanist philosophy focusing on people's allegiances and relations with each other." It is one of the founding principles of the new Republic of South Africa emphasizing "...the need for unity or consensus in decision-making, as well as the need for a suitably humanitarian ethic to inform those decisions".

What a nice meaning for this simple word. I look at much of the professional success I've had over the last 15 odd years, and I can unequivocally say that the main reason for that success has been the amazing people I've worked with---I am what I am truly because of the teams that I've been a part of. Ubuntu!

Tuesday, May 27, 2008

Remote Agent

The Phoenix Mars Lander touched down successfully on the surface of Mars on Sunday. It was no mean feat. The landing sequence was considered so risky that the official mission page on the NASA web site describes it as Seven Minutes of Terror! They note that the international history of the space age, only five of 13 attempts to land on Mars have succeeded.

Check out this great picture of the part of the landing sequence where Phoenix descends into the Martian atmosphere with its parachute.

A crucial mission sequence is called a critical sequence. In a critical sequence you get one and only one chance to to execute the sequence right, with a failed sequence implying a failed mission. Critical sequences include landings (like the one that Phoenix executed flawlessly), orbit insertions (such as Cassini inserting itself into Saturn's orbit), and some flybys (such as Stardust's flyby of Comet Wild 2 to collect and return comet dust).

Talk of critical sequences reminds me of our work on the Remote Agent. I was at NASA through much of the 1990s working as a research scientist in an Artificial Intelligence (AI) research lab. Some time in 1995 the NASA Administrator, Dan Goldin, gave an inspiring speech. In it he outlined a vision that would allow NASA to significantly step up space exploration in spite of shrinking budgets. The key, he said, was to develop new technologies in such diverse areas as propulsion, MEMS, and autonomy. And he established the New Millennium Program to carry out his vision.

We (i.e., a group of AI researchers) were energized by this speech and decided to do something about it. Specifically, we thought that we could build a Remote Agent---an on-board autonomous agent to provide high-level control to achieve mission objectives. We pitched our idea to spacecraft engineers at JPL. Naturally, the spacecraft engineers were skeptical---after all, what did a bunch of AI researchers know about spacecraft autonomy? But they were open minded---they said they'd believe us if we could show them how the Remote Agent would handle Cassini's critical sequence (Saturn orbit insertion) in a simulated environment. And to make sure that the simulated environment didn't abstract away the hard parts of the critical sequence, they assigned an accomplished spacecraft engineer to lead the project.

We worked hard for the next 5 months or so, leading up to a demonstration of the system to various senior engineers at JPL. Everything was going smoothly, when suddenly an unexpected bug hit us (unexpected in the sense that it was not part of the demonstration script, though we were aware of this bug in our earlier testing but hadn't had the chance to track it down and fix it). The bug was in the communication between the Remote Agent and the underlying spacecraft simulation, and it manifested itself as a failure of the main rocket engines just as they were being turned on to slow down the spacecraft in preparation for orbit insertion!

The Remote Agent responded beautifully to this unexpected turn of events! It noticed that the main rocket engine had failed, switched to the back up engine, replanned the insertion sequence, and successfully inserted the spacecraft into orbit around Saturn (all in simulation of course---the real Cassini mission didn't use the Remote Agent!).

The success of this demonstration led directly to doing this for real on Deep Space 1, the first of the New Millennium missions. On May 17, 1999, the Remote Agent took control of Deep Space 1 to start the first of two on-board autonomy experiments. Being in mission control during these experiments was one of the most thrilling moments of my professional life!

You can read all about the Remote Agent here and about the actual experiments here. No discussion of a space mission is complete without a photograph of the spacecraft. I wanted to include a photograph of me with Deep Space 1 (in the testing bay at JPL). Unfortunately, I couldn't locate that photograph :-( So instead, you'll have to make do with the following poster. I have a big version of this poster at home---a parting gift from my NASA colleagues when I left NASA.

Sunday, May 25, 2008

Phoenix Mars Lander

Looks like the Phoenix has landed! I am always amazed by how complex space missions succeed when the engineers get essentially only one chance to get it right.

Check out the first images from Mars here.

Growing Vegetables in EarthBoxes

Some days ago I wrote about the possibility of growing vegetables in EarthBoxes. Last weekend I converted cheap talk into action---I bought 3 EarthBoxes and planted a variety of vegetables! Here's a picture of 2 of the EarthBoxes (I got the third after I took this photograph).

The EarthBox on the right has two varieties of tomatoes, while the EarthBox on the left has basil, serrano peppers, and two varieties of bell peppers (two golden bells and a purple bell). The third EarthBox is full of bush beans. So following Michael Pollan's advice, I've taken the first step toward growing some of our own food (given my expertise in the matter, we'll be happy if we get at least one meal out of this!).

In terms of the the EarthBox promise of "virtually no effort", it's looking pretty good right now. Over the last week, taking care of the plants has involved simply topping off the water reservoir through the fill tube that you can see at the front right of each EarthBox. It takes less than 5 minutes a day. And, except for the basils, the plants are looking well hydrated. (The basils' leaves are slightly curled up, which may mean that they aren't getting quite enough water, though they're clearly getting water; they're not obviously dried up or anything.) So there is a good chance that we might actually land up with something we can eat!

Saturday, May 24, 2008

Nerdy dads

Ha! I'm not the only nerdy dad reading The Number Devil to his kids!

And everyone in our household is thoroughly enjoying it, I may add.

Sunday, May 18, 2008

What is Mathematics: GCD

This is the third in the series of posts on the book What is Mathematics. This post is about the the Greatest Common Denominator (GCD) of a pair of numbers.

The GCD of a pair of positive integers a and b (denoted here as gcd(a, b)) is simply the largest positive integer that divides both a and b. The Euclidean algorithm is a simple way to compute the GCD. The Euclidean algorithm is based on the observation that for any positive integers a and b there exist integers q and r with 0 ≤ r < b such that

a = b × q + r

Note that r is simply the remainder when you divide a by b. From this it is easy to show that u is a common divisor of a and b if and only if u is a common divisor of b and r. Since the set of common divisors are identical, it follows that the greatest common divisors are also identical, i.e.,

gcd(a, b) = gcd(b, r)

To get the Euclidean algorithm, one simply applies the above result recursively to gcd(b, r) until we get to rn-1 and rn such that gcd(rn-1, rn) = 0. When this happens, we can conclude that gcd(a, b) = rn. (We would, of course, use mathematical induction to prove this formally.)

One important property of gcd(a, b) that can be derived from the above is that there exist positive or negative integers k and l such that

gcd(a, b) = k × a + l × b

Using this, the book presents a simple proof of the fundamental theorem of arithmetic. The proof starts by using the above property to show that if a prime p divides a × b then it divides either a or b. One can then easily show that purportedly different prime factorizations of a number are in fact identical.

Finally, the book introduces Euler's function. Two integers a and b are said to be relatively prime if

gcd(a, b) = 1

Euler's function, usually denoted φ(n), is the number of integers from 1 to n that are relatively prime with n. Note, in particular, φ(1) = 1 and φ(p) = p - 1 when p is prime. The book claims that Euler's function is a number-theoretical function of great importance (though it does not expand on this claim immediately).

One interesting property of Euler's function is the generalization of Fermat's little theorem: if n is any integer and a is relatively prime with n then

aφ(n) ≡ 1 (mod n)

Wednesday, May 14, 2008

Farm Bill

Greg Mankiw's recent post on the Farm Bill discusses various reasons why President Bush wants to veto the bill. If even some of these reasons are true (and I have no reason to doubt them), this looks like pork at its best and the bill deserves to be vetoed.

Tuesday, May 13, 2008

Growing vegetables

Several weeks ago Michael Pollan, author of books such as The Omnivore's Dilemma, had an article entitled Why Bother in the NY Times Magazine. The article starts by asking why we as individuals should bother to do anything about climate change. He outlines a number of reasons why it doesn't seem to make sense to bother ranging from the puniness of our efforts, to the negation of our efforts by others, to a lack of clarity on what exactly would help.

But then he proceeds to argue that given the seriousness of the consequences of not bothering, it is absolutely essential to do ones part to reverse climate change:

Going personally green is a bet, nothing more or less, though it’s one we probably all should make, even if the odds of it paying off aren’t great. Sometimes you have to act as if acting will make a difference, even when you can’t prove that it will.

Okay, so you've decided to do something about it. But what? Pollan has a suggestion:

But the act I want to talk about is growing some — even just a little — of your own food.

An interesting thought. My kids have been wanting me to garden with them for quite some time now. But having grown up in a high-rise in a big city, I didn't get to learn anything about gardening, let alone developing a love for it...:-( So I don't have a green thumb, and I've generally viewed gardening as a chore, and so have not obliged my kids.

But over the weekend, when reading the Google blog post on growing ones food, I was reminded of EarthBox. The EarthBox is a

... maintenance-free, award-winning, high-tech growing system controls soil conditions, eliminates guesswork and more than doubles the yield of a conventional garden-with less fertilizer, less water and virtually no effort.

Note particularly the "virtually no effort" clause and, of course, I'm a sucker for "high-tech systems"...:-) So I'm going to get one of these to see if I can at least grow some tomatoes for a few salads and the occasional pasta sauce. I'm not sure that using an EarthBox is exactly what Michael Pollan had in mind. But it's the closest I'm going to get to growing my own food!

Thursday, May 8, 2008

Memories of Independence Days

Today is the 60th anniversary of Israel's independence. Alon has a very nice post on the occasion, describing what his father did on the day Israel gained independence. In reading that post, I was reminded of the story of another friend's father's memory of Indian independence.

My friend's father and his family lived in Lahore (in present day Pakistan). Being Hindu, when news of independence and the partition of India and Pakistan arrived, it was clear that they had to flee Lahore. But how to flee safely---atrocities were being committed in the name of religion. Turns out that they had a loyal Muslim driver who offered to drive them across the border. So the whole family hid in the back of a lorry (truck) and the Muslim driver drove it toward the border. Along the way a mob stopped the lorry and asked to search the back for fleeing Hindus. But the driver stared down the mob, using his own religious persuasion to convince the mob that there was no need to look in the back. Fortunately, the mob let the lorry go without a search and they escaped to India. My friend's father went on to become a very senior government official in India.

For a powerful dramatization of Lahore right before and during independence, I strongly recommend the movie 1947 Earth starring Aamir Khan and Nandita Das. It's a story told through the eyes of a little Parsi girl growing up in Lahore (the Parsis were viewed as being neutral in the Hindu-Muslim conflict). Aamir Khan is absolutely amazing and the climactic scene in the movie haunts me to this day.

Sunday, May 4, 2008

What is Mathematics: Prime numbers

This is the second in the series of posts on the book What is Mathematics. This post is about some important results on prime numbers.

One of the most basic results is that there are infinitely many primes. As a kid in middle or high school, I remember being fascinated by the proof of this result. The proof, given by Euclid, is straightforward and is a great example of an "indirect proof". You start by assuming that there are only a finite number of primes. Then consider the number, n, that is one more than the product of all these primes. Since n is larger than all the primes, it is not prime, and must have prime factors. But n is clearly not divisible by any of these primes (by construction, dividing by any prime leaves a remainder of 1). This leads to a contradiction, so that our assumption must be false and there are, indeed, infinitely many primes.

The fundamental theorem of arithmetic (again given by Euclid) states that every integer greater than 1 can be factored into a product of primes in only one way. The book has a very nice proof of this theorem (again an "indirect proof" that starts by assuming that the prime factorization is not unique).

There have been various attempts to find formulae that produce primes, though no such general formula has been found. However, the prime number theorem provides a remarkable formula for the distribution of primes. Let An denote the number of primes from 1 to n. Then the prime number theorem states that (An / n) tends to (1 / log n) as n tends to infinity (where log n is the natural logarithm of n). The proof of this theorem requires advanced methods and is not discussed in the book (though there's apparently some discussion toward the end).

The book introduces some interesting open problems related to primes. Of these, the most famous is Goldbach's conjecture. This conjecture states that any even number greater than 2 can be expressed as a sum of two primes. Goldbach proposed this in 1742 in a letter to Euler, asking Euler to prove or disprove it. Empirically the result appears to be true. However, while much progress has been made, the proof remains elusive.

Finally, a fundamentally important theorem due to Fermat (also called Fermat's little theorem) states that if p is a prime that does not divide the integer a then

ap - 1 ≡ 1 (mod p)

where (mod p) says that the congruence (≡) is modulo p (i.e., both sides have the same remainder when divided by p). The proof in the book is based on observing that no pair of multiples of a of the form ka (where 1 ≤ k < p) can be congruent modulo p. For if k1ak2a (mod p), then (k1 - k2)a ≡ 0 (mod p) which implies that a is divisible by p (since both k1 and k2 are less than p). Similarly, ka cannot be congruent to 0 (mod p). Thus, each of the above (p - 1) multiples of a are congruent to (a distinct) one of 1, 2, ..., (p - 1), and therefore

1 × 2 × ... × (p - 1) ap - 1 ≡ 1 × 2 × ... × (p - 1) (mod p)

from which the result follows.

On a side note, Fermat's little theorem plays a central role in the Miller-Rabin primality test. Primality testing is essential to the RSA public key cryptosystem that is used to secure various web-based activities like ecommerce, online banking, and online stock trading using https.

Friday, May 2, 2008

Better hair care

There's been a lot of talk about how electronic health care records can dramatically transform and improve the health care industry. But Alon has a better idea: hair care records!

Securing your wireless network

In a previous post I questioned the utility of securing your wireless network. Nonetheless, suppose you do want to secure it. Ars Technica has this great post on the ABCs of securing your wireless network. Check it out if you're at all concerned about the issue. Here's the bottom line:

Generally speaking, any router that supports WPA is "good enough" in terms of its overall security. WEP, as we've previously stated, is an "only if you must" protocol, but it's still a better option than transmitting in the clear.

WEP (Wired Equivalent Privacy) is an older security standard than WPA (Wi-Fi Protected Access). While there are different flavors of WPA available, Ars Technica notes that the differences between them are small compared to the improvement of WPA over WEP. So use WPA (unless you want your Nintendo DS to connect to your network--the DS doesn't support WPA).

Early in the article they debunk various myths that: more harm than good by lulling the end-user into a false sense of security.

These include hiding or changing the SSID (the name of your wireless network), disabling DHCP, or filtering MAC addresses. This last method happens to be the one I use currently. From a security perspective:

The problem with filtering by MAC address, however, is that these addresses are easily faked and readily detected by anyone using appropriate monitoring software.

However, it may be appropriate given my earlier post about not really needing security:

...filtering MAC addresses is the only one with even a minimal level of value. MAC address filtering can keep obnoxious and non-tech-savvy neighbors from easily freeloading on your wireless network, but it won't do much else.

Sunday, April 20, 2008

What is Mathematics: Mathematical Induction

This is the first in my series on some interesting and important techniques and results described in the book What is Mathematics. The first chapter introduces the natural numbers, 1, 2, 3, ... In Leopold Kronecker's words: "God created the natural numbers; everything else is man's handiwork."

After introducing the basics of natural numbers, the authors introduce the fundamental technique of the principle of mathematical induction. This is a very simple, yet powerful, method for proving theorems about an infinite sequence of cases. In its simplest form, suppose you want to prove that a property An for all positive integers n (e.g., An might be the proposition that (1 + p)n ≥ (1 + np) for any p > -1). The principle of mathematical induction states that you can prove this using two steps:
  1. First, you prove that A1 holds, i.e., the property holds when n = 1 (often called the base case).
  2. Next, for every r ≥ 1 you show that if Ar holds then Ar+1 also holds (this is often called the inductive step).
One can see that the above two steps serve to establish An for all n ≥ 1.
The proposition that (1 + p)n ≥ (1 + np) for any p > -1 can be easily established using mathematical induction (this will prove to be a useful little inequality).

The principle of mathematical induction needs to be applied with care. The authors demonstrate the pitfalls of this method with the following "proof" that all numbers are, in fact, equal!

Let An be the statement "If a and b are any two positive integers such that max(a, b) = n, then a = b". The base case is certainly true: when n = 1, a and b must both be 1 (being positive integers). For the inductive case, assume Ar holds and let a and b be such that max(a, b) = r + 1. Clearly, then max(a - 1, b - 1) = r, and hence by assumption a - 1 = b - 1. Hence a = b. So An holds for all n. In particular, for any a and b, if max(a, b) = r, then Ar holds and hence for any a and b, a = b!

Can you see the hole in this proof?

What is Mathematics

In a previous post I mentioned that I was going to get a copy of the book What is Mathematics by Richard Courant and Herbert Robbins. Well, I've now got a copy of it and I'm reading through it. And I'm thoroughly enjoying it! The book is a mathematics book---it talks about the techniques and results in mathematics, often with proofs (at least when the proofs don't involve advanced techniques). But it's written in a very conversational style---as if Courant was sitting across the dining table from you and sharing with you his love of mathematics. (That imagery makes sense only if you can imagine discussing mathematics at the dinner table...:-)

As I read this book, I thought I'd put together a series of posts highlighting some of the most interesting and important methods and theorems that I encounter. Part of my purpose is to share this with you (and encourage you to get the book); but the other part is to summarize it for my own benefit. I'll keep this post updated with the list of all posts in this series. Here are the posts.
  1. Mathematical induction
  2. Prime numbers
  3. GCD

Thursday, April 3, 2008

International Bar-Code of Life

My friend Alon has a great post about his recent visit to Costa Rica where he learned about the International Bar-Code of Life Project from his host Dan Janzen, a Kyoto Prize winning biologist.

Monday, March 31, 2008

Mathematics books

My friend Vineet visited the US last week and I had a very enjoyable discussion with him. Vineet has a great interest in all things mathematical. So, not surprisingly, one of the interesting things we talked about was an old blog post of his that listed a series of great books on mathematics. You can go to the post to check out all his recommendations, but here I'm going to highlight three of them. Vineet recommended the first two for my kids:
  • Sideways Arithmetic from Wayside School by Louis Sacher.
    Louis Sacher is the author of the very popular Wayside School series; our kids have loved these books. This Sideways Arithmetic book consists of "50 mindboggling math puzzles". For example, the first puzzle in the books is: elf + elf = fool. The problem in this case is to identify the number that each letter stands for.
  • The Number Devil by Hans Magnus Enzensberger.
    This book looked even more interesting. It's about a young boy who visits a "...bizarre magical land of number tricks with the number devil as his host." And in this land, kids are introduced to all kinds of mathematical concepts including prime numbers ("prima donnas"), irrational numbers ("unreasonable"), and roots ("rutabagas"). Sounds fun and educational!

And for older kids (or adults like me!), he recommended "What is Mathematics?" by Richard Courant (after whom NYU's Courant Institute is named) et al. This was a book originally published in 1941, and recently revised in 1996! Any book in print since 1941 has to be a classic. This isn't a book about mathematics (in the sense that it isn't about the philosophy of mathematics or about meta-mathematics). Rather, it provides an elementary approach to the ideas and methods of mathematics. Albert Einstein apparently said of this book "A lucid representation of the fundamental concepts and methods of the whole field of mathematics...Easily understandable"!

I think I'm going to get all three books (for my kids and for me!) and check them out.

Thursday, March 20, 2008

David Swensen on investing

Stock markets all over the world are in free fall. With the demise of Bear Stearns, the sub-prime crisis is only appearing to get worse. Oil prices are going through the roof, and even food prices are surging. How should we react to all this? Specifically, how should we change our investment portfolio?

The answer, says, David Swensen is "do nothing"! David Swensen has run the hugely successful Yale endowment fund since 1988. He was interviewed by the NY Times about a month ago. His basic advice is:

Don’t try anything fancy. Stick to a simple diversified portfolio, keep your costs down and rebalance periodically to keep your asset allocations in line with your long-term goals.
For most people, he recommends a very basic approach: use index funds, exchange-traded funds and other low-cost instruments, and stick to your long-term asset allocation — even when the markets are in tumult.

And that's exactly what I'm doing, following the ETF portfolio I've written about in the past. I have no idea when the markets are going to turn around. And that's exactly the point: if I was to drastically change my asset allocation to react to current events, I'd have to figure out when to get back to this strategy (presumably when the markets start to recover). Which means I'd have to be right twice to make this strategy work---once to know when to sell (I'm already late on this) and then to know when to buy back into the market (I'm sure I'd be late for that too). Much simpler to leave well alone, and incur no trading or tax costs.

What strategy are you using?

Wednesday, March 19, 2008

My God, it's full of stars!

Arthur C. Clarke died early today in Sri Lanka. The NY Times has a very good obituary. Growing up, I was a great fan of Clarke's writing. His most famous work, 2001: A Space Odessey, is of course a classic book and movie (Stanley Kubrick co-wrote the movie). I must be the only person in the world who's read the book but not seen the movie! It turns out that Clarke wrote the book after he co-wrote the movie with Kubrick (based on Clarke's original ideas). He felt compelled to write the book because he disagreed with Kubrick's "...obscurism and mysticism..." in the movie (see here for a discussion). So the movie and the book disagree in exactly those areas where Clarke disagreed with Kubrick. In fact, Dave Bowman's famous line in the book as he enters the monolith ("My God, it's full of stars") does not appear in the movie!

While 2001 was an amazing book, he had other equally amazing books. I remember being particularly enthralled by Rendezvous with Rama, a fascinating story of an encounter with a huge, cylindrical alien craft that comes swooping into the solar system. And then, of course, there's his frightening classic Childhood's End, featuring aliens who look like devils. Clarke gave me a lot of joy with these and other books. I hope he finds that where he's gone now is full of stars!

Tuesday, March 18, 2008

Sudhir Venkatesh on the Colbert Report

I've written previously about Sudhir Venkatesh and his series on watching The Wire with thugs. Venkatesh recently appeared on the Colbert Report. Check out his short 5 minute appearance:

(Thanks to the folks over at Freakonomics for the pointer.)

On a related note, Ashish had pointed out in the comments to my previous note that Venkatesh has also done research on the economics of street prostitution. Not surprisingly then, Venkatesh has some interesting comments on the the recent events involving Eliot Spitzer.


It's been about 3 weeks since I last posted a entry. It's not that there haven't been things to write about---there were lots of interesting things going on. But I just got really busy with one thing and another (conference reviewing, taxes, actual work, being sick, ...!). Hopefully things are getting better now.

Monday, February 25, 2008

Sub-prime mortgage mess explained

You're all no doubt familiar with the sub-prime mortgage disaster that has wreaked havoc on the stock market. But do you really understand what this mess is all about? If you don't, here's something to help you. There's a slide show making the rounds that uses cartoons to do a great job of explaining the mess (original author unknown)! I found it in a recent post by Roger Ehrenberg. Here it is for your viewing pleasure:

Download explanation_of_sub_prime_issue.pps

Saturday, February 23, 2008

Solar panels for the home

The San Jose Mercury News recently reported that Severin Borenstein, a business school professor at UC Berkeley and the Director of the UC Energy Institute, says that:

Installing solar panels on homes is an economic "loser" with the costs far outweighing the financial benefit ...
The technology, using photovoltaic panels to generate electricity, is not economically competitive with fossil fuels and costs more than other renewable fuels

The solar industry, naturally, disagrees with Borenstein's conclusions. But I have to say that, based on the little research I've done, I have not been convinced about the financial utility of installing solar panels. In my mind, the primary benefit of installing solar panels appears to be the good feeling one gets from doing something about climate change. Borenstein explicitly notes that

...he didn't take into account the feel-good benefit or societal value of installing a solar system on your roof.

But is there a different way to get these benefits without incurring the financial costs of installing solar panels? I think there is.

Some utilities allow you to opt for "green energy" alternatives; for a small premium one can buy energy from renewable sources. For example, Palo Alto Green is a program that allows you to buy your electricity from renewable sources for a premium of only 1.5 cents per kWh. Currently, 97.5% of the this renewable energy is from wind and the remaining 2.5% from solar. (Of course, the actual energy delivered to your home isn't guaranteed to be from a renewable source, but the utility promises to buy the right amount of electricity from renewable sources based on the usage by subscribers to this program.)

We've been subscribers to this program for some time now. And based on Borenstein's analysis, I don't think I'm going to rush in to install solar panels on our roof. Rather, I'll let the utilities install large solar farms or other renewable energy sources, and get the "good feeling" by supporting their efforts. Presumably, the utilities will ensure that these renewable sources are cost effective.
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