A stochastic model for the evolution of a growing population is proposed, in order to explain empirical power-law distributions in the frequency of family names as a function of the family size. Preliminary results show that the predicted exponents are in good agreement with real data. The...

Gradient-based approaches to direct policy search in reinforcement learning have received much recent attention as a means to solve problems of partial observability and to avoid some of the problems associated with policy degradation in value-function methods. In this paper we introduce GPOMDP,...

Purpose – Recent research indicates that the random walk hypothesis (RWH) approximately describes the behavior of major dollar exchange rates during the post‐1973 float. The present analysis seeks to examine the profitability of currency futures trading rules that assume that spot exchange...

Purpose – The purpose of this paper is to advocate the use of processual rather than the common variance‐theoretic approaches to the study of groups and organizational processes. There is a proliferation of paradigms and a lack of cumulation in organization science. This paper argues that...

Purpose – In this two‐part series, this paper seeks to consider certain intriguing aspects of randomness, the basic mathematical concept used to model financial risk and other unknown quantities in the physical world. Design/methodology/approach – Part 1 applies concepts from quantum...

Purpose – The purpose of the paper, in this two‐part series, is to consider certain intriguing aspects of randomness, the basic mathematical concept used to model financial risk and other unknown quantities in the physical world. Design/methodology/approach – In Part 2 of the paper, the...

Purpose – Recent research indicates that the random walk hypothesis (RWH) approximately describes the behavior of major dollar exchange rates during the post-1973 float. The present analysis seeks to examine the profitability of currency futures trading rules that assume that spot exchange...

We introduce two new measures of network robustness and apply them to four different strategies. The measures are independent from the number of nodes in the network and have the strong potential to cover a large portfolio of applications. Using the Monte-Carlo methods, we demonstrate how to...

Exact solutions are rare for non-Markovian random walk models even in 1D, and much more so in 2D. Here we propose a 2D genuinely non-Markovian random walk model with a very rich phase diagram, such that the motion in each dimension can belong to one of 3 categories: (i) subdiffusive, (ii)...

In this paper we propose a statistical physics approach to experimental results on bacterial mutations (Escherichia coli). We get scaling laws that describe some generic traits and suggest some features of the underlying dynamical structure for the considered evolution process. Our main...