In: Europhysics Letters, 2009, vol. 88, no. 3, p. 38005
Most news recommender systems try to identify users' interests and news' attributes and use them to obtain recommendations. Here we propose an adaptive model which combines similarities in users' rating patterns with epidemic-like spreading of news on an evolving network. We study the model by computer agent-based simulations, measure its performance and discuss its robustness against bias and...
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In: The European Physical Journal B, 2009, vol. 71, no. 4, p. 565-571
We consider a simple market where a vendor offers multiple variants of a certain product and preferences of both the vendor and potential buyers are heterogeneous and possibly even antagonistic. Optimization of the joint benefit of the vendor and the buyers turns the toy market into a combinatorial matching problem. We compare the optimal solutions found with and without a matchmaker, examine...
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In: International Review of Financial Analysis, 2009, vol. 18, no. 1-2, p. 34-39
When assets are correlated, benefits of investment diversification are reduced. To measure the influence of correlations on investment performance, a new quantity—the effective portfolio size—is proposed and investigated in both artificial and real situations. We show that in most cases, the effective portfolio size is much smaller than the actual number of assets in the portfolio and that it...
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In: Journal of Statistical Mechanics, 2009, vol. 2009, no. 2, p. P02014
One of the key socioeconomic phenomena to explain is the distribution of wealth. Bouchaud and Mézard (2000 Physica A 282 536) have proposed an interesting model of an economy based on trade and investments of agents. In the mean-field approximation, the model produces a stationary wealth distribution with a power law tail. In this paper we examine characteristic timescales of the model and...
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In: The European Physical Journal B, 2008, vol. 64, no. 2, p. 293-300
We introduce a fully probabilistic framework of consumer product choice based on quality assessment. It allows us to capture many aspects of marketing such as partial information asymmetry, quality differentiation, and product placement in a supermarket.
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In: Europhysics Letters, 2007, vol. 80, no. 6, p. 68003
Information overload in the modern society calls for highly efficient recommendation algorithms. In this letter we present a novel diffusion-based recommendation model, with users' ratings built into a transition matrix. To speed up computation we introduce a Green function method. The numerical tests on a benchmark database show that our prediction is superior to the standard recommendation...
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In: The European Physical Journal B, 2008, vol. 63, no. 2, p. 273-278
We investigate a network model based on an infinite regular square lattice embedded in the Euclidean plane where the node connection probability is given by the geometrical distance of nodes. We show that the degree distribution in the basic model is sharply peaked around its mean value. Since the model was originally developed to mimic the social network of acquaintances, to broaden the degree...
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In: Physica A: Statistical Mechanics and its Applications, 2008, vol. 387, no. 24, p. 6151-6158
Financial markets, with their vast range of different investment opportunities, can be seen as a system of many different simultaneous games with diverse and often unknown levels of risk and reward. We introduce generalizations to the classic Kelly investment game [J.L. Kelly, IEEE Transactions on Information Theory 2 (1956) 185–189] that incorporates these features, and use them to investigate...
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In: Physica A: Statistical Mechanics and its Applications, 2008, vol. 387, no. 12, p. 2889-2908
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In: Physical Review E, 2007, vol. 76, no. 4, p. 046115
One-mode projecting is extensively used to compress bipartite networks. Since one-mode projection is always less informative than the bipartite representation, a proper weighting method is required to better retain the original information. In this article, inspired by the network-based resource-allocation dynamics, we raise a weighting method which can be directly applied in extracting the...
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