Janusz A. Holyst

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BACKGROUND E-communities, social groups interacting online, have recently become an object of interdisciplinary research. As with face-to-face meetings, Internet exchanges may not only include factual information but also emotional information--how participants feel about the subject discussed or other group members. Emotions in turn are known to be(More)
In many social dilemmas, individuals tend to generate a situation with low payoffs instead of a system optimum (“tragedy of the commons”). Is the routing of traffic a similar problem? In order to address this question, we present experimental results on humans playing a route choice game in a computer laboratory, which allow one to study decision behavior(More)
Sentiment analysis programs are now sometimes used to detect patterns of sentiment use over time in online communication and to help automated systems interact better with users. Nevertheless, it seems that no previous published study has assessed whether the position of individual texts within ongoing communication can be exploited to help detect their(More)
We present an empirical study of user activity in online BBC discussion forums, measured by the number of posts written by individual debaters and the average sentiment of these posts. Nearly 2.5 million posts from over 18 thousand users were investigated. Scale free distibutions were observed for activity in individual discussion threads as well as for(More)
An economic system which exhibits chaotic behaviour has been stabilized on various periodic orbits by use of the Ott-Grebogi-Yorke method. This procedure has been recently applied to controlling chaotic phenomena in physical, chemical and biological systems. We adopt this method successfully for Feichtinger's generic model of two competing firms with(More)
We study the influence of noise on information transmission in the form of packages shipped between nodes of hierarchical networks. Numerical simulations are performed for artificial tree networks, scale-free Ravasz-Barabási networks as well for a real network formed by email addresses of former Enron employees. Two types of noise are considered. One is(More)
The interest in supply chain networks and their analysis as complex systems is rapidly growing. The physical approach to the topic of production networks relies on the concept of heterogeneous interacting agents. The interaction among agents is considered as a repeated process of orders and production. The dynamics of production in the supply chain network(More)
The model of scientific paradigms spreading throughout the community of agents with memory is analyzed using the master equation. The case of two competing ideas is considered for various networks of interactions, including agents placed at Erdős-Rényi graphs or complete graphs. The pace of adopting a new idea by a community is analyzed, along with the(More)
Julian Sienkiewicz, Marcin Skowron, Georgios Paltoglou, and Janusz A. Ho lyst Faculty of Physics, Center of Excellence for Complex Systems Research, Warsaw University of Technology, Koszykowa 75, PL-00-662 Warsaw, Poland 2 Interaction Technologies Group, Austrian Research Institute for Artificial Intelligence, Freyung 6/3/1a, A-1010 Vienna, Austria 3 School(More)