Despite significant advances in characterizing the structural properties of complex networks, a mathematical framework that uncovers the universal properties of the interplay between the topology and the dynamics of complex systems continues to elude us. Here we develop a self-consistent theory of dynamical perturbations in complex systems, allowing us to systematically separate the contribution of the network topology and dynamics. The formalism covers a broad range of steady-state dynamical processes and offers testable predictions regarding the system’s response to perturbations and the development of correlations. It predicts several distinct universality classes whose characteristics can be derived directly from the continuum equation governing the system’s dynamics and which are validated on several canonical network-based dynamical systems, from biochemical dynamics to epidemic spreading. Finally, we collect experimental data pertaining to social and biological systems, demonstrating that we can accurately uncover their universality class even in the absence of an appropriate continuum theory that governs the system’s dynamics.
Universality in network dynamics Baruch Barzel & Albert-László Barabási
To be a long-term investor requires thematic investing because markets and economies are complex adaptive systems, according to Tim Hodgson, global head of the thinking-ahead group at Towers Watson.
Hodgson told delegates at the Towers Watson Ideas Exchange in Sydney that economies and markets are complex and adaptive, their path is not random and the future is not predictive.
“We don’t live in a linear world. We must hold truths in our head while we navigate the future. A single market price cannot reflect this,” he says.
Towers Watson believes that there are a number of interconnected issues that will converge in the next decades, and which it outlines in its 2013 secular outlook on thematic investing, which will require transformational change.
“It is coming straight at you: the asset owner and you have to deal with it whether you like it or not,” he says.
Recognition of the interconnectedness of these issues is essential.
Hodgson says traditional investment thinking is drawn heavily from economics, which has separate disciplines. The micro side of economics is well developed and the industry is disciplined in how to optimise a portfolio, value a company or price a derivative, all in isolation. But the macro side, including the emergence of bubbles, is almost completely unknown.
Commercial aviation is feasible thanks to the complex socio-technical air transportation system, which involves interactions between human operators, technical systems, and procedures. In view of the expected growth in commercial aviation, significant changes in this socio-technical system are in development both in the USA and Europe. Such a complex socio-technical system may generate various types of emergent behavior, which may range from simple emergence, through weak emergence, up to strong emergence. The purpose of this paper is to demonstrate that agent-based modeling and simulation allows identifying changed and novel rare emergent behavior in this complex socio-technical system. (...)
Agent-based modeling and simulation of emergent behavior in air transportation Bouarfa S, Blom HA, Curran R, Everdij MH Complex Adaptive Systems Modeling 2013, 1:15 (15 August 2013)
Conventional wisdom holds that complex structures evolve from simpler ones, step-by-step, through a gradual evolutionary process, with Darwinian selection favoring intermediate forms along the way. But recently some scholars have proposed that complexity can arise by other means—as a side effect, for instance—even without natural selection to promote it. Studies suggest that random mutations that individually have no effect on an organism can fuel the emergence of complexity in a process known as constructive neutral evolution.
Center for Complexity in Business (CCB) at the Robert H. Smith School of Business at the University of Maryland is is the world’s first (and only) research center specializing in the application of complex systems methods to business problems.
Betty Cares's insight:
Looks to be a very interesting conference. Jeff will consider attending. Anyone else?
Ever noticed that certain things on a Facebook page load faster than others? This is often the case with even the simplest of websites, but with a site the size of Facebook’s globe-spanning social network, the divide is in some ways more pronounced. Facebook, you see, serves information from two very different collections of data.
Most data is stored inside a good old fashioned database — the open source mainstay MySQL — but the social networking giant also uses a second system to house data that’s accessed with particular frequency. This system is known as Memcached, and it’s a common thing inside the massive data centers that underpin the world’s largest websites. Memcached stores data in the memory subsystems of the servers that drive Facebook, rather than slower hard disks. Facebook engineers call it “hot data.” Basically, this means that the data you’re more likely to visit is more likely to load at speed.
The rub is that juggling both MySQL and Memcached isn’t the easiest of tasks for the engineers that build and operate the Facebook machine. But in recent years, the company has built a new system that seeks to ease the use of these two data stores. It’s called TAO, short for “The Associations and Objects,” and it’s been used on the site for “several” years now.
Under certain market conditions, cartels arise naturally without collusion. This raises important questions over how the behavior should be controlled.
The price of gas is a puzzle. Monitor the average price in gas stations in a particular city and it will vary dramatically, sometimes in a matter of hours and often in ways that appear cyclical.
Economist have long scratched their heads over this kind of pattern. One explanation is that this behaviour emerges when two competing companies change their pricing strategy at each stage by reacting to the other. The resulting behaviours are known as Edgeworth Price Cycles.
The problem is that gas station prices are not controlled by two competing players but many competing retailers. It’s easy to assume that the many-body problem produces similar patterns but nobody has been able to show this.
Until now. Today Tiago Peixoto and Stefan Bornholdt, physicists at the University of Bremen in Germany, show how a more complicated model with many buyers and sellers reproduces this kind of behaviour.
But it also goes further. Peixoto and Bornholdt say that when condition are right, cartel-like behaviour emerges naturally without collusion between sellers.
The legendary Complex Adpative Systems researcher, Lazlo Barabasi, now runs a Network Science research center at Northeastern U. I was VERY surprised to find his courses' slides with commentary available to review and download here.
Here is the program from NETMOB 2013 held at MIT last week -- It is billed as an international conference on the analysis of mobile phone datasets. Some fascinating topics here--did anyone in my network attend???
Transcript of Stephen Wolfram’s SXSW 2013 presentation. Discusses his vision of what computation will do for people in the future. Not only as it applies to science and knowledge discovery, but also as it pertains to personal well-being.
Networks are ubiquitous and the scientific discipline of network science has flourished in the last decade. As a means to study complex interactions, two particular application areas are social and information science. On the one hand side, the www as a pool of hyper-linked information can be represented with the help of networks (and this representation is the basis for google’s Page-rank algorithm), on the other hand side services like facebook, twitter or flickr provide the means for people to establish social networks of never-seen size – and hence provide the basis for what is now called computational sociology.
The scope of this this summer school is to provide PhD students and early PostDocs with a comprehensive 1-week insight into the “power of networks” in an information science and social media setting. In Six to nine lectures, established and well-known researchers (from Europe, US and Asia) will present cutting-edge research as well as provide the participants with valuable insight into challenges and methods.
The Summer School will take place from 10th to 15th June in Höllviken (south of Sweden, 1h by train from Copenhagen, Denmark), right after NetSci 2013.
The goal of Guided Self-Organization (GSO) is to leverage the strengths of self-organization while still being able to direct the outcome of the self-organizing process. GSO typically has the following features: (i) an increase in organization (structure and/or functionality) over some time; (ii) the local interactions are not explicitly guided by any external agent; (iii) task-independent objectives are combined with task-dependent constraints.
A number of attempts have been made to formalize aspects of GSO within information theory, thermodynamics and dynamical systems. However, the lack of a broadly applicable mathematical framework across multiple scales and contexts leaves GSO methodology incomplete. Devising such a framework and identifying common principles of guidance are the main themes of the GSO workshops.
Of particular interest are well-founded, but general methods for characterizing GSO systems in a principled way, with the view of ultimately allowing them to be guided toward pre-specified goals. In general, various entropy methods drawing from, and overlapping with, information theory, thermodynamics, nonlinear dynamics and graph theory are relevant, while quantifying complexity and its sources is a common theme.
Deadline for manuscript submissions: 31 January 2014
This paper provides a logical framework for complexity economics. Complexity economics builds from the proposition that the economy is not necessarily in equilibrium: economic agents (firms, consumers, investors) constantly change their actions and strategies in response to the outcome they mutually create. This further changes the outcome, which requires them to adjust afresh. Agents thus live in a world where their beliefs and strategies are constantly being “tested” for survival within an outcome or “ecology” these beliefs and strategies together create. Economics has largely avoided this nonequilibrium view in the past, but if we allow it, we see patterns or phenomena not visible to equilibrium analysis. These emerge probabilistically, last for some time and dissipate, and they correspond to complex structures in other fields. We also see the economy not as something given and existing but forming from a constantly developing set of technological innovations, institutions, and arrangements that draw forth further innovations, institutions and arrangements.(...)
Complexity Economics: A Different Framework for Economic Thought W. Brian Arthur SFI WP 13-04-012
SOCIAL networks stand accused of being enemies of productivity. According to one popular (if questionable) infographiccirculating online, the use of Facebook, Twitter and other such sites at work costs the American economy $650 billion each year. Our attention spans are atrophying, our test scores declining, all because of these “weapons of mass distraction.”
Yet such worries have arisen before. In England in the late 1600s, very similar concerns were expressed about another new media-sharing environment, the allure of which seemed to be undermining young people’s ability to concentrate on their studies or their work: the coffeehouse. It was the social-networking site of its day.
Like coffee itself, coffeehouses were an import from the Arab world. England’s first coffeehouse opened in Oxford in the early 1650s, and hundreds of similar establishments sprang up in London and other cities in the following years. People went to coffeehouses not just to drink coffee, but to read and discuss the latest pamphlets and news-sheets and to catch up on rumor and gossip.
Coffeehouses were also used as post offices. Patrons would visit their favorite coffeehouses several times a day to check for new mail, catch up on the news and talk to other coffee drinkers, both friends and strangers. Some coffeehouses specialized in discussion of particular topics, like science, politics, literature or shipping. As customers moved from one to the other, information circulated with them.
This event, hosted by the Institute of Quantitative Social Science at Harvard University and organized by the Center of Complex Network Research at Northeastern University on June 17th, brings together social scientists, computer scientists, economists, physicists and mathematicians to discuss the quantitative laws and patterns behind success.
Pierre Azoulay James A. Evans Santo Fortunato Gautam Mukunda Alexander M. Petersen Camille Sweeney Arnout van de Rijt Brian Uzzi Christoph Riedl Nicola Perra Duncan Watts Chaoming Song
Researchers at IBM, using movement data collected from millions of cell-phone users in Ivory Coast in West Africa, have developed a new model for optimizing an urban transportation system.
The IBM model prescribed changes in bus routes around the around Abidjan, the nation’s largest city. These changes—based on people’s movements as discerned from cell-phone records—could, in theory, slash travel times 10 percent.
Glen Whitney stands at a point on the surface of the Earth, north latitude 40.742087, west longitude 73.988242, which is near the center of Madison Square Park, in New York City. Behind him is the city’s newest museum, the Museum of Mathematics, which Whitney, a former Wall Street trader, founded and now runs as executive director. He is facing one of New York’s landmarks, the Flatiron Building, which got its name because its wedge- like shape reminded people of a clothes iron. Whitney observes that from this perspective you can’t tell that the building, following the shape of its block, is actually a right triangle—a shape that would be useless for pressing clothes—although the models sold in souvenir shops represent it in idealized form as an isosceles, with equal angles at the base. People want to see things as symmetrical, he muses. He points to the building’s narrow prow, whose outline corresponds to the acute angle at which Broadway crosses Fifth Avenue.
“The cross street here is 23rd Street,” Whitney says, “and if you measure the angle at the building’s point, it is close to 23 degrees, which also happens to be approximately the angle of inclination of the Earth’s axis of rotation.”