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Modeling Temporal Activity Patterns in Dynamic Social Networks

May 10, 2013 Comments (0)

The focus of this work is on developing probabilistic models for user activity in social networks by incorporating the social network influence as perceived by the user. For this, we propose a coupled Hidden Markov Model, where each user's activity evolves according to a Markov chain with a hidden state that is influenced by the collective activity of the friends of the user. We develop generalized Baum-Welch and Viterbi algorithms for model parameter learning and state estimation for the...

Accounting and the Formation of Share Market Prices Over Time: A Mathematical Institutional Economic Analysis Through Simulation and Experiment

May 9, 2013 Comments (0)

This paper develops an agent-based model to examine the emergent dynamic properties of share market price formation over time, with a view on financial market stability under alternative accounting regimes. In the model, individual heterogeneous investors interact with each other and with institutional devices which are an accounting system (related to the business firm) and a price system (related to the Share Exchange). These interactions provide mechanisms for transmission through which...

Global Networks Must be Re-Designed

May 2, 2013 Comments (0)

The increasing interdependencies between the world’s technological, socio-economic, and environmental systems have the potential to create global catastrophic risks. We may have to re-design many global networks, otherwise they could turn into "global time bombs".

Rethinking Economics Using Complexity Theory

May 2, 2013 Comments (0)

In this paper we argue that if we want to find a more satisfactory approach to tackling the major socio-economic problems we are facing, we need to thoroughly rethink the basic assumptions of macroeconomics and financial theory. Making minor modifications to the standard models to remove "imperfections" is not enough, the whole framework needs to be revisited.

Toolism! A Critique of Econophysics

May 1, 2013 Comments (0)

Economists are fond of the physicists’ powerful tools. As a popular mindset Toolism is as old as economics but the transplants failed to produce the same successes as in their aboriginal environment. Economists therefore looked more and more to the math department for inspiration. Now the tide turns again. The ongoing crisis discredits standard economics and offers the chance for a comeback. Modern econophysics commands the most powerful tools and argues that there are many occasions for their...

A Fokker-Planck description for the queue dynamics of large tick stocks

May 1, 2013 Comments (0)

Motivated by empirical data, we develop a statistical description of the queue dynamics for large tick assets based on a two-dimensional Fokker-Planck (diffusion) equation, that explicitly includes state dependence, i.e. the fact that the drift and diffusion depends on the volume present on both sides of the spread. "Jump" events, corresponding to sudden changes of the best limit price, must also be included as birth-death terms in the Fokker-Planck equation. All quantities involved in the...

Government Solvency, Austerity and Fiscal Consolidation in the OECD: A Keynesian Appraisal of Transversality and No Ponzi Game Conditions

May 1, 2013 Comments (0)

This paper investigates the relevance of the No-Ponzi game condition for public debt (i.e. the public debt growth rate has to be lower than the real interest rate, a necessary assumption for Ricardian equivalence) and of the transversality condition for the GDP growth rate (i.e. the GDP growth rate has to be lower than the real interest rate). First, on the unbalanced panel of 21 countries from 1961 to 2010 available in OECD database, those two conditions were simultaneously validated only for...

Selection and Influence in Cultural Dynamics

May 1, 2013 Comments (0)

One of the fundamental principles driving diversity or homogeneity in domains such as cultural differentiation, political affiliation, and product adoption is the tension between two forces: influence (the tendency of people to become similar to others they interact with) and selection (the tendency to be affected most by the behavior of others who are already similar). Influence tends to promote homogeneity within a society, while selection frequently causes fragmentation. When both forces are...

How important tasks are performed: peer review

April 25, 2013 Comments (0)

The advancement of various fields of science depends on the actions of individual scientists via the peer review process. The referees' work patterns and stochastic nature of decision making both relate to the particular features of refereeing and to the universal aspects of human behavior. Here, we show that the time a referee takes to write a report on a scientific manuscript depends on the final verdict. The data is compared to a model, where the review takes place in an ongoing competition...

Time evolution of Wikipedia network ranking

April 25, 2013 Comments (0)

We study the time evolution of ranking and spectral properties of the Google matrix of English Wikipedia hyperlink network during years 2003 - 2011. The statistical properties of ranking of Wikipedia articles via PageRank and CheiRank probabilities, as well as the matrix spectrum, are shown to be stabilized for 2007 - 2011. A special emphasis is done on ranking of Wikipedia personalities and universities. We show that PageRank selection is dominated by politicians while 2DRank, which combines...