¿Cooperación Espontánea?

Excelente video de Steven Strongatz en TED explicando cómo y por qué seres vivos (y no vivos) se organizan descentralizadamente.

http://www.ted.org/index.php/talks/steven_strogatz_on_sync.html

How physics can explain why some countries are rich and others are poor

Published in Slate
Tuesday, August 21, 2007

Milton Friedman, Meet Richard Feynman How physics can explain why some countries are rich and others are poor.By Tim HarfordPosted Saturday, Aug. 18, 2007, at 7:07 AM ET
If economics can tell us something useful about crime, marriage, or carpooling—as I believe it can—then other academic disciplines should have something to tell us about economies. Last month, Science published an example that may turn out to be important. Two physicists, Cesar Hidalgo and Albert-László Barabási, and two economists, Bailey Klinger and Ricardo Hausmann, have been drawing unusual pictures of economic "space" that promise a deeper understanding of the biggest question in economics: why poor countries are poor.
There are many explanations, but some are easier to test than others. One very plausible account of why at least some poor countries are poor is that there is no smooth progression from where they are to where they would be when rich. For instance, to move from drilling oil to making silicon chips might require simultaneous investments in education, transport infrastructure, electricity, and many other things. The gap may be too far for private enterprise to bridge without some sort of coordinating effort from government—a "big push."
That is an old and intuitive idea in economics, but as an informal argument it leaves a lot to be desired. For a start, while plausible, it might not be true. If it is true, it might be far more so for some kinds of economy than for others. And if there is to be a big push, in which direction should it go?

Testing the idea took three steps. First, economists at the National Bureau of Economic Research broke down each country's exports into 775 distinct products. Next, Hausmann and Klinger used that data to measure how similar each product is to each other product. If every major apple exporter also exports pears, and every major pear exporter also exports apples, then the data are demonstrating apples and pears to be similar.
Presumably, both economies would have fertile soil, agronomists, refrigerated packing plants, and ports. For the third step, Hausmann and Klinger called upon Hidalgo and Barabási, who specialize in mapping and analyzing networks. The result was a map of the relationships between different products in an abstract economic space. (And look at more maps here.) Apples and pears are close together; oil production is a long way away from anything else.
The physicists' map shows each economy in this network of products, by highlighting the products each country exported. Over time, economies move across the product map as their export mix changes. Rich countries have larger, more diversified economies, and so produce lots of products—especially products close to the densely connected heart of the network. East Asian economies look very different, with a big cluster around textiles and another around electronics manufacturing, and—contrary to the hype—not much activity in the products produced by rich countries. African countries tend to produce a few products with no great similarity to any others.
That could be a big problem. The network maps show that economies tend to develop through closely related products. A country such as Colombia makes products that are well connected on the network, and so there are plenty of opportunities for private firms to move in to, provided other parts of the business climate allow it. But many of South Africa's current exports—diamonds, for example—are not very similar to anything.
If the country is to develop new products, it will mean making a big leap. The data show that such leaps are unusual.
None of this is proof that other development prescriptions—provide financing, fight corruption, cut red tape, and lower trade barriers—are useless. Nor is it a green light for ham-fisted industrial policy. Klinger warns: "It's easy to take the policy implication too far and start trying to pick and choose where to settle in the product space." But it is a big step forward. Policy-makers should take note, and economists, too.

The Trouble with Dynasties

By Pamela W. Laird

Why doesn’t George W. Bush fire Attorney General Alberto Gonzales? Like Donald Rumsfeld before him and, more recently, Paul Wolfowitz, Gonzales is causing President Bush political embarrassment and costing him political support. The President’s supporters praise his personal loyalty to subordinates. His critics charge him with arrogance and unwillingness to admit error. But both sides, while recognizing Bush’s loss of political capital, fail to recognize his protection of something he regards as more critical: his social capital.

Full article

China's corruption crackdown enters the bedroom

The Guardian Unlimited
April 30, 2007

China's 6.5 million civil servants were warned today they could be fired for keeping a mistress or neglecting elderly relatives, under new ethical guidelines aimed at curbing rampant corruption.

Prime minister Wen Jiabao signed the code of conduct, which will extend deep into the private lives of bureaucrats once it comes into effect in June.

Officials face possible dismissal if they are caught with a prostitute or abusing drugs, according to the People's Daily.

Full Article

Web of friends at heart of power

By IAN JOHNSTON (01/07/2005)

KIRSTY Wark has intimate links with Scottish Labour and many of its senior supporters.
She was a close family friend of the late first minister Donald Dewar and even shared a garden with him when they were neighbours. It was Mr Dewar who appointed her to the panel to choose the design of the Scottish Parliament. She was impressed by Enric Miralles - the eventual winner - and they were said to have become close friends.

Amid mounting claims of "cronyism", it was Ms Wark’s television company, Wark Clements - set up in 1990 with her husband Alan Clements - which was chosen to make a documentary about the building of Holyrood. There was outrage when Ms Wark and the BBC refused to hand over all the film shot during the making of the documentary, called The Gathering Place, to the Fraser inquiry into the handling of the construction. The counsel to the inquiry, John Campbell, QC, who questioned her, was a friend - she had been a bridesmaid at his wedding. Despite this, however, Mr Campbell made his displeasure at her refusal to hand over the tapes abundantly clear.

Ms Wark was backed up by her colleague, then controller of BBC Scotland, John McCormick, who insisted handing over the tapes would clash with the BBC’s policies. Mr McCormick has since left the BBC and recently took up a post as chairman of the Scottish Qualifications Authority, an appointment made by the Executive.

Another friend of Ms Wark, James Boyle, is currently chairman of the Scottish Executive’s cultural commission. He previously worked at the BBC and was also on the board of Wark Clements, when he was paid £21,000 as a consultant, according to company documents from April 2003. He also previously chaired the Scottish Arts Council, which includes Glasgow City Council Lord Provost Elizabeth Cameron on its board.

Jack McConnell’s wife Bridget is Glasgow City Council’s director of cultural and leisure services. She is also a member of the Heritage Lottery Fund (HLF) board in Scotland, chairwoman of Vocal, the influential local government cultural body, a fellow of the Royal Society of Arts and a member of the board of the Royal Scottish Academy of Music and Drama.

She appeared to have a very public falling out with Mr Boyle after commission "sources" said she and council officials should stop interfering in cultural issues. However, Mrs McConnell and Mr Boyle are still thought to be friends and were seen together at a one-man-show by former No 10 spin doctor Alistair Campbell in Glasgow last year.

Another Mr Boyle, John, the former Motherwell FC chairman and millionaire businessman, is another close friend of Ms Wark and Mr Clements, with strong links to the Labour Party. He has a house on Majorca not far from Ms Wark’s holiday home.

Mr Boyle, who is currently in Australia, bought a £1 million share in Wark Clements and was on the board of the company in April 2003, according to the latest accounts filed with Companies House. He has made substantial donations to the Labour Party, including one of £20,000 in 1999. Mr Boyle is close to millionaire businessman Willie Haughey, the boss of City Refrigeration Holidays, who is chairman of Scottish Enterprise Glasgow and a major donor to Labour. In 2003, the former Celtic director gave £330,000 to the party.

He sits on the board of Scottish Enterprise Glasgow with Ms Wark’s husband.

The influence of Wark Clements increased when the firm merged with Muriel Gray’s Ideal World Productions, its leading rival in Scotland, to become IWC Media.

Do Lenders Favor Politically Connected Firms? Rent Provision in an Emerging Financial Market

by Asim Ijaz Khwaja and Atif Mian
The Quarterly Journal of Economics, 2005, vol. 120, issue 4, pages 1371-1411

Abstract: Corruption by the politically connected is often blamed for economic ills, particularly in less developed economies. Using a loan-level data set of more than 90,000 firms that represents the universe of corporate lending in Pakistan between 1996 and 2002, we investigate rents to politically connected firms in banking. Classifying a firm as "political" if its director participates in an election, we examine the extent, nature, and economic costs of political rent provision. We find that political firms borrow 45 percent more and have 50 percent higher default rates. Such preferential treatment occurs exclusively in government banks-private banks provide no political favors. Using firm fixed effects and exploiting variation for the same firm across lenders or over time allows for cleaner identification of the political preference result. We also find that political rents increase with the strength of the firm's politician and whether he or his party is in power, and fall with the degree of electoral participation in his constituency. We provide direct evidence against alternative explanations such as socially motivated lending by government banks to politicians. The economy-wide costs of the rents identified are estimated to be 0.3 to 1.9 percent of GDP every year.

Why social networks are different from other types of networks?

By M. E. J. Newman and Juyong Park

ABSTRACT
We argue that social networks differ from most other types of networks, including technological
and biological networks, in two important ways. First, they have non-trivial clustering or network transitivity, and second, they show positive correlations, also called assortative mixing, between the degrees of adjacent vertices. Social networks are often divided into groups or communities, and it has recently been suggested that this division could account for the observed clustering. We demonstrate that group structure in networks can also account for degree correlations. We show using a simple model that we should expect assortative mixing in such networks whenever there is variation in the sizes of the groups and that the predicted level of assortative mixing compares well with that observed in real-world networks.

Paper here

Assortative model for social networks

By Michele Catanzaro, Guido Caldarelli, and Luciano Pietronero

ABSTRACT: In this Brief Report we present a version of a network growth model, generalized in order to describe the behavior of social networks. The case of study considered is the preprint archive at cul.arxiv.org. Each node corresponds to a scientist, and a link is present whenever two authors wrote a paper together. This graph is a nice example of degree-assortative network, that is, to say a network where sites with similar degree are connected to each other. The model presented is one of the few able to reproduce such behavior, giving some insight on the microscopic dynamics at the basis of the graph structure.

Paper here

Are Randomly Grown Graphs Really Random?

By D. S. Callaway, J. E. Hopcroft, J. M. Kleinberg, M. E. J. Newman, and S. H. Strogatz

Abstract
We analyze a minimal model of a growing network. At each time step, a new vertex is added; then, with probability $\delta$, two vertices are chosen uniformly at random and joined by an undirected edge. This process is repeated for $t$ time steps. In the limit of large $t$, the resulting graph displays surprisingly rich characteristics. In particular, a giant component emerges in an infinite-order phase transition at $\delta = 1/8$. At the transition, the average component size jumps discontinuously but remains finite. In contrast, a static random graph with the same degree distribution exhibits a second-order phase transition at $\delta = 1/4$, and the average component size diverges there. These dramatic differences between grown and static random graphs stem from a positive correlation between the degrees of connected vertices in the grown graph--older vertices tend to have higher degree, and to link with other high-degree vertices, merely by virtue of their age. We conclude that grown graphs, however randomly they are constructed, are fundamentally different from their static random-graph counterparts.

Link here

Why Personal Ties Cannot Be Bought?

By Casella & Hanaki (2006)
American Economic Review, Papers and Proceedings May 2006, p.p. 261-264

The unambiguous message of our model is that networking transmits information effectively only if its cost is low. When networking is free, it is preferred to signaling by both firms and workers almost without exception. But it is never a very precise mechanism, and if its cost is higher, firms’ hiring decisions interact with workers’ selfselection preventing endogenous improvements in precision. At high cost, signaling transmits information more accurately and supplants networking completely. We are somewhat surprised to conclude in qualified support of the sociologists’ position: networks work best when they are unintentional, and thus free by-products of people’s social life: ethnic, religious, family networks. In this case, they are extremely difficult to substitute with a market mechanism. Nor is it easy to mimic these spontaneous network through the intentional, and thus costly, creation of personal ties, because such action distorts, as opposed to favoring, the transmission of information. If ties are costly, market mechanisms are superior.

Paper here

Winners don't take all: Characterizing the competition for links on the web

By Pennock, Flake, Lawrence, Glover, and Giles (2002)

ABSTRACT
As a whole, the World Wide Web displays a striking ‘‘rich get richer’’ behavior, with a relatively small number of sites receiving a disproportionately large share of hyperlink references and traffic. However, hidden in this skewed global distribution, we discover a qualitatively different and considerably less biased link distribution among subcategories of pages—for example, among all university homepages or all newspaper homepages. Although the connectivity distribution over the entire web is close to a pure power law, we find that the distribution within specific categories is typically unimodal on a log scale, with the location of the mode, and thus the extent of the rich get richer phenomenon, varying across different categories. Similar distributions occur in many other naturally occurring networks, including research paper citations, movie actor collaborations, and United States power grid connections. A simple generative model, incorporating a mixture of preferential and uniform attachment, quantifies the degree to which the rich nodes grow richer, and how new (and poorly connected) nodes can compete. The model accurately accounts for the true connectivity distributions of category-specific web pages, the web as a whole, and other social networks.

Paper here

A classic: The diameter of the world wide web

by Albert, Jeong and Barabasi (1999)

"... we find that the average of d over all pairs of vertices follows hdi = 0.35+2.06 log(N), indicating that the web forms a small-world network"

Full article here

Power Laws, Weblogs, and Inequality

By Clay Shirky

"Diversity plus freedom of choice creates inequality, and the greater the diversity, the more extreme the inequality..."

Complete article here

Celebrity in social networks: how can we avoid the power law distribution?

By Ben Werdmuller

"In any information ecosystem, there is an observable tendency for a few sources on a topic - be they journals, websites or people - to have a massive following, a significantly smaller number to have a medium number of followers, and then a final, largest group to have a much smaller number of regular readers. This can be witnessed in the Technorati Top 100: the top 100 blogs range from around 80,900 unique links to 4,900 (quite a decrease), yet Technorati track 26.6 million sites. If the downward link trend continues across all 26.6 million, most weblogs have at most one a handful of links - and therefore a correspondingly small number of readers. I've been wondering for a while how best to verbalise this..."

complete article here

The topology of covert conflict

By Shishir Nagaraja, Ross Anderson

Abstract. Often an attacker tries to disconnect a network by destroying nodes or edges, while the defender counters using various resilience mechanisms. Examples include a music industry body attempting to close down a peer-to-peer file-sharing network; medics attempting to halt the spread of an infectious disease by selective vaccination; and a police agency trying to decapitate a terrorist organisation. Albert, Jeong and Barab´asi famously analysed the static case, and showed that vertex-order attacks are effective against scale-free networks. We extend this work to the dynamic case by developing a framework based on evolutionary game theory to explore the interaction of attack and defence strategies. We show, first, that naive defences don’t work against vertex-order attack; second, that defences based on simple redundancy don’t work much better, but that defences based on cliques work well; third, that attacks based on centrality work better against clique defences than vertex-order attacks do; and fourth, that defences based on complex strategies such as delegation plus clique resist centrality attacks better than simple clique defences. Our models thus build a bridge between network analysis and evolutionary game theory, and provide a framework for analysing defence and attack in networks where topology matters. They suggest definitions of efficiency of attack and defence, and may even explain the evolution of insurgent organisations from networks of cells to a more virtual leadership that facilitates operations rather than directing them. Finally, we draw some conclusions and present possible directions for future research.

Paper here

Economics: an emerging small world?

Goyal, van der Leij, Moraga-Gonzalez (2003)

Abstract
This paper examines the small world hypothesis. The first part of the paper presents empirical evidence on the evolution of a particular world: the world of journal publishing economists during the period 1970-2000. We find that in the 1970's the world of economics was a collection of islands, with the largest island having about 15% of the population. Two decades later, in the 1990's the world of economics was much more integrated, with the largest island covering close to half the population. At the same time, the distance between individuals on the largest island had fallen significantly. Thus we believe that economics is an an emerging small world.

What is it about the network structure that makes the world small? An exploration of the micro aspects of the network yields three findings: one, the average number of co-authors is very small but increasing; two, the distribution of co-authors is very unequal; and three, there exist a number of `stars', individuals who have a large number of co-authors (25 times the average number) most of whom do not write with each other. Thus the economics world is a set of inter-connected stars.

We take the view that individuals decide on whether to work alone or with others; this means that individual incentives should help us understand why the economics world has the structure it does. The second part of the paper develops a simple theoretical model of co-authorship. The main finding of the model is that in the presence of productivity di®erentials and a shortage of high productivity individuals, inter-connected stars will arise naturally in equilibrium. Falling costs of communication and increasing credit for joint research leads to greater co-authorship and this is consistent with the growth in the size of the giant component.

Legal Institutions and Informal Networks

By Ethan Bueno de Mesquita and Matthew Stephenson, 2006
Journal of Theoretical Politics 18(1): 40–67

ABSTRACT
The relationship between third-party contract enforcement and informal networks raises important sociological, political, and economic questions. When economic activity is embedded in social structures, what are the implications of third-party contract enforcement for the scope and nature of economic relations? What determines whether individuals rely on formal legal institutions or informal networks to sustain trade relationships? Do legal institutions erode informal networks? We develop a model in which a trade-off exists between size and sustainability of networks. By adding the possibility of feebased, enforceable contracts, we provide a theoretical explanation for the coexistence of legal contract enforcement and an informal economy. We find that legal enforcement has little effect on networks until law becomes sufficiently inexpensive, at which point small decreases in the cost of law have dramatic effects on network size and the frequency of use of the legal system.

Paper here

The Economics of Social Networks

By Matthew O. Jackson

Abstract
The science of social networks is a central field of sociological study, a major application of random graph theory, and an emerging area of study by economists, statistical physicists and computer scientists. While these literatures are (slowly) becoming aware of each other, and on occasion drawing from one another, they are still largely distinct in their methods, interests, and goals. Here, my aim is to provide some perspective on the research from these literatures, with a focus on the formal modeling of social networks and the two major types of models: those based on random graphs and those based on game theoretic reasoning. I highlight some of the strengths, weaknesses, and potential synergies between these two network modeling approaches.

Paper here