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In my salad days, I whiled away the hours in Geography class, forming cricket teams. If the devil, for example, were to form a cricket team, what would her eleven consist of?  Not only one must determine the eleven, but the order in which they will go in to bat as well. One’s school mates would be busy constructing Jesus’s eleven and so on. This was a far more engaging than learning that Chunking was a conurbation and Singapore an entreport. It wasn’t long before I decided that cricket teams were dull and I wondered about academic departments. It came to  pass that I would occupy myself in  Biology class between organizing  snail races (for which I was caught, and told I was just the sort of person who burnt down schools) and designing God’s mathematics departments. Try it. Department of size 25, say. You can have anyone you want living or dead, who would you put in?

Imagine my surprise to hear that the publisher Elsevier has software (which they call sci-val strata) to design a department for an ominous sounding collection called research managers (there’s a group destined for the B-ark if ever there was one). Plumbing their bibliometric database, the software allows one to `drag and drop’ researches into a group and see what would happen. I’m a little vague on the `see what would happen part’. I guess they have various metrics  to `measure’ the impact of the new team. If one could include  salary information and turn it into a mobile device app, one would have a delightful way to pass the time in seminars.

I became a fan of Jared Diamond after having read his book “Guns, Germs and Steel” that nicely explain why Europeans came to America and history did not evolve the other way around. His second book, “Collapse”, which explains how attitude to environmental factors affect the survival success of societies only strengthened the bond between us. So when I saw that he has a third book, “Natural Experiments of History”, I immediately ordered it from

First thing I noticed when I got the book was that Diamond is one of the editors of this book, which collects eight essays written by different authors (one essay was written by Diamond). This fact did not discourage me and I remained hopeful.

As my readers know, I do not believe in lab experiments of human behavior. The essays in this book study natural experiments – they analyze real data and try to see how one factor affects other factors. Here the data do not lie, and the only question is whether you believe that no factors were forgotten in the analysis (and whether the analysis was properly executed).

One chapter that was especially interesting contrasts the number of slaves taken from the various regions of Africa during the slave trade, to the level of economic development of that region today. The negative relation, which may be expected, is nicely exhibited.

Another interesting chapter contrasts the taxation method that the British imposed on various regions in India (landlord method, in which local landlords were responsible for collecting taxes from the locals, and paying taxes to the government, pocketing the difference; village method, in which each village was responsible for collecting taxes from its inhabitants; and personal method), and the development level of the region today, in terms of investment in education, hospitals etc.

The book was certainly not a waste of money; I heartily recommend all my readers to read “Guns, Germs and Steel” and “Collapse”!

In those happy occassions when a paper of mine is accepted for publication and I get the proofs from the journal, I usually just sign the consent for publication form without taking more than a glimpse at the proofs. The way I see it, my job is to get papers into journals, after that the papers should fend to themselves. Besides, the journal’s changes are usually either harmless or for the better.

Last, week, however, was an exception, not in my action because I still just signed the form as usual, but in my response to the proofs. Even after the quick glimpse I noticed that something is wrong, and after reading further I was horrified to see that all the references I made to myself (and, as readers of this blog know, I talk about myself a lot) were replaced by references to myself and my imaginary friends. In short, the word `I’ was eliminated from the paper and replaced with `we’. I thought I will just be furious about it for a couple of days and then forget the whole thing, but after a week of fuming with no forgeting in the horizon, I have no other option but to move to plan B, which is venting my indignation on you, dear TLTC readers.

Now look, I am cool with “we” that means “one”, to celebrate the fact that the validity of mathematical statements is independent of the person who happens to claim them, as in “Dividing by \pi, we get that the game admits an equilibrium”. But sometimes the automatic replacement of `I’ with `we’ garbles the meaning of the sentence. When I write “I call such a sequence of variables a random play”, the singular pronoun implies that this is not a universally recognized definition, but one that I have invented for the current paper. Change this “I” to “we”, as the journal did, and the implication is lost. And sometimes `we’ for `one’ is just ridiculous, as in “We review Martin’s Theorem in the appendix”. It is one thing to say that every intelligent creature recognizes that the game admits an equilibrium, and another thing to say that every intelligent creature reviews Martin’s Theorem in the appendix.

In some cases the editors were gracious enough to grant my singular identity but then they changed the person. “I thank, I proved, I don’t know” became “The author thanks, the author proved, the author doesn’t know”, which is even worse since it reminds me the way Israeli politicians speak about themselves.

What annoys me of here is the complete arbitrariness of the rule. The word “I” is perfectly legitimate in everyday language but banned from scientifc writing. I can’t think of any other word that is discriminated in this way. I guess next time if I don’t want to be called `we’ or `the author’ in my own papers then I will use all the puculiarities of academic writing like `it is conjuctured’, as if conjectures grow up on trees without somebody taking responsibility for them. I never understood why writers use these constructions so often. Now we know.

Yet another game theory puzzle, one that is always fun to come across, especially on Terence Tao’s blog. In the version I know the islanders are less devoted to their religion and more jealous of their wives, but the point is the same. Does it make any difference when a fact that everybody already knows is publicly announced ?

In bargaining theory, a “disagreement point” or “threat point” is the policy which is implemented if no agreement is reached. Typically, it is bad for both sides, but may be worse for one. The disagreement point has a profound impact on the outcome of negotiations, even if it never comes to pass. (In theory-land, say in Nash or Rubinstein bargaining, there is never disagreement, but the threat of disagreement is a crucial determinant of the outcome.)


Obviously, in our government’s current situation, the disagreement point is a shutdown. TV pundits have been speculating for weeks about which side this hurts more. But this isn’t the only imaginable disagreement point. The system could decree that, say, last year’s budget gets extended automatically if no new budget is passed. This would drastically impact the negotiations (favoring the Democrats in this particular case.) My question to anyone who knows the history of government better than I do is: How did we come to have a system where the government shuts down unless a new budget is passed each year? And do other countries differ on this point?

I think I will give it as the official solution to the data mining question in our core statistics course




The opening line of Myerson’s obituary for  John Harsanyi reads:

When a scholar publishes a paper, it is a letter sent to unknown recipients.

It is in this way I first met Lionel McKenzie. A curiosity, I suppose, of those in service of reason’s empire. We meet on the page first and in person later. It is from McKenzie that I first learnt the difference between economic theory and mathematics. The stalking horse for the lesson is the existence of Walrasian equilibrium. Which is a more general model: one with decreasing returns to scale or one with constant returns to scale in the production function? Mathematically, the first. But, the first is also an implicit constraint on entrepreneurial activity. Thus, the second could be considered more general.

Mckenzie passed away in October 2010. I was reminded of him recently by two incidents. The first, was the occasion of a memorial conference at the U of Rochester two weeks ago. Whilst aware of his contributions to GE, I was not aware of the `murderer’s row’ of students he had `fathered’. The second, an interesting paper by Weintraub on the `race’ for priority for existence of Walrasian equilibrium in which McKenzie plays a prominent role. For those with an interest in how credit is or is not apportioned as well as how history is recorded (or not), it makes for a fascinating read….particularly when the names of referees are mentioned!

I love playing cards with my two kids. One game we are fond of is “Carré Couper”. I found the following description of the game in AOL-answers (for non-French speakers, carré = square, couper = to cut):

The game starts by each couple to set a secret code so they’ll be able to speak during the game. That’s because they can’t see each other cards. The aim of the game is to create a foursome of the same card rank in one of the partner’s hands and to prevent from the other couple to set it’s own foursome. At the beginning each player gets 4 cards. The rest stay in the fund. On each round 4 cards are taken out from the fund and put face up on the table. A player may switch cards with these on the table, though he may not hold more than 4 cards. A player will try to hint his partner on his cards or on the rivals cards using the secret code. When all the players have no more intrest in the 4 cards on the table, the cards are taken out of the game. So obivously, One cannot create a foursome with these cards ranks. The game ends when a player recognizes his body has a foursome and declares “Carré” or when a player thinks the rival couple have a foursome and declares “Couper” before they declare “Carré“. You set points – 1 for “Carré, 4 for “Double Carré“,a pair may intentionally choose to wait until each pair member will have a foursome. You should declare “double Carré”. 2 points for “Couper” and 1 point for the other pair for a wrong “Couper”. “Double Coupe” and “Double Carré Couper” are very rare and should get many points.

The problem that we face is that we are three, and often in lack of a forth partner. We thought of the following adaptation of the game to three players: the players sit in a cycle, each pair of players selects a secret code. Each player’s goal is to reveal to the player on his right when he creates a foursome of the same card rank, while detecting when that player has such a foursome. Thus, when I create a foursome, I should reveal it to the player on the right, while hiding it from the player on the left.

Everything looked fine until we realized that there is a srategic aspect to this game: player 1 may be willing to reveal to player 2 his secret code with player 3 so that player 3 cannot win a point. When we realized this point, my older son refused to play the game. We tried to tell him that we will not do it; after all, we are family and can count on each other. But he refused whatsoever.

So if there are three of you somewhere who try playing this variation, please tell me how it goes.

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