http://jasss.soc.surrey.ac.uk Journal of Artificial Societies and Social Simulation: For the exploration and understanding of social processes by means of computer simulation en-GB Copyright Journal of Artificial Societies and Social Simulation Fri, 03 Feb 2012 16:07:27 +0000 jasss@surrey.ac.uk (Nigel Gilbert) http://jasss.soc.surrey.ac.uk/gifs/JASSS-small.jpg http://jasss.soc.surrey.ac.uk erezh51@gmail.com (Erez Hatna and Itzhak Benenson) Article http://jasss.soc.surrey.ac.uk/15/1/6.html http://jasss.soc.surrey.ac.uk/15/1/6.html Wed, 01 Feb 2012 12:59:00 +0000 Erez Hatna and Itzhak Benenson: The Schelling model of segregation is an agent-based model that illustrates how individual tendencies regarding neighbors can lead to segregation. The model is especially useful for the study of residential segregation of ethnic groups where agents represent householders who relocate in the city. In the model, each agent belongs to one of two groups and aims to reside within a neighborhood where the fraction of 'friends' is sufficiently high: above a predefined tolerance threshold value F. It is known that depending on F, for groups of equal size, Schelling's residential pattern converges to either complete integration (a random-like pattern) or segregation. The study of high-resolution ethnic residential patterns of Israeli cities reveals that reality is more complicated than this simple integration-segregation dichotomy: some neighborhoods are ethnically homogeneous while others are populated by both groups in varying ratios. In this study, we explore whether the Schelling model can reproduce such patterns. We investigate the model's dynamics in terms of dependence on group-specific tolerance thresholds and on the ratio of the size of the two groups. We reveal new type of model pattern in which a portion of one group segregates while another portion remains integrated with the second group. We compare the characteristics of these new patterns to the pattern of real cities and discuss the differences. a.j.heppenstall@leeds.ac.uk (Kirk Harland, Alison Heppenstall, Dianna Smith and Mark Birkin) Article http://jasss.soc.surrey.ac.uk/15/1/1.html http://jasss.soc.surrey.ac.uk/15/1/1.html Wed, 01 Feb 2012 12:58:00 +0000 Kirk Harland, Alison Heppenstall, Dianna Smith and Mark Birkin: There are several established methodologies for generating synthetic populations. These include deterministic reweighting, conditional probability (Monte Carlo simulation) and simulated annealing. However, each of these approaches is limited by, for example, the level of geography to which it can be applied, or number of characteristics of the real population that can be replicated. The research examines and critiques the performance of each of these methods over varying spatial scales. Results show that the most consistent and accurate populations generated over all the spatial scales are produced from the simulated annealing algorithm. The relative merits and limitations of each method are evaluated in the discussion. o.mannion@auckland.ac.nz (Oliver Mannion, Roy Lay-Yee, Wendy Wrapson, Peter Davis and Janet Pearson) Article http://jasss.soc.surrey.ac.uk/15/1/8.html http://jasss.soc.surrey.ac.uk/15/1/8.html Wed, 01 Feb 2012 12:57:00 +0000 Oliver Mannion, Roy Lay-Yee, Wendy Wrapson, Peter Davis and Janet Pearson: JAMSIM (JAva MicroSIMulation) is an innovative synthesis of open source packages that provides an environment and set of features for the creation of dynamic discrete-time microsimulation models that are to be executed, manipulated and interrogated by non-technical, policy-oriented users. Combining the leading open source statistical package R and one of the foremost agent-based modelling (ABM) graphical tools Ascape, JAMSIM is available as an open source tool, for public reuse and modification. Here we describe microsimulation, our functional requirements, a review of tools used by other micro-simulators and an evaluation of existing software, followed by the architecture, features and use of JAMSIM. christophe.le_page@cirad.fr (Christophe Le Page, Nicolas Becu, Pierre Bommel and François Bousquet) Article http://jasss.soc.surrey.ac.uk/15/1/10.html http://jasss.soc.surrey.ac.uk/15/1/10.html Wed, 01 Feb 2012 12:56:00 +0000 Christophe Le Page, Nicolas Becu, Pierre Bommel and François Bousquet: This paper describes how the Cormas platform has been used for 12 years as an artefact to foster learning about agent-based simulation for renewable resource management. Among the existing generic agent-based simulation platforms, Cormas occupies a tiny, yet lively, place. Thanks to regular training sessions and an electronic forum, a community of users has been gradually established that has enabled a sharing of ideas, practices and knowledge, and the emergence of a genuine community of practice whose members are particularly interested in participatory agent-based simulation. mfonoberova@aimdyn.com (Maria Fonoberova, Vladimir A. Fonoberov, Igor Mezic, Jadranka Mezic and P. Jeffrey Brantingham) Article http://jasss.soc.surrey.ac.uk/15/1/2.html http://jasss.soc.surrey.ac.uk/15/1/2.html Wed, 01 Feb 2012 12:55:00 +0000 Maria Fonoberova, Vladimir A. Fonoberov, Igor Mezic, Jadranka Mezic and P. Jeffrey Brantingham: We perform analysis of data on crime and violence for 5,660 U.S. cities over the period of 2005-2009 and uncover the following trends: 1) The proportion of law enforcement officers required to maintain a steady low level of criminal activity increases with the size of the population of the city; 2) The number of criminal/violent events per 1,000 inhabitants of a city shows non-monotonic behavior with size of the population. We construct a dynamical model allowing for system-level, mechanistic understanding of these trends. In our model the level of rational behavior of individuals in the population is encoded into each citizen's perceived risk function. We find strong dependence on size of the population, which leads to partially irrational behavior on the part of citizens. The nature of violence changes from global outbursts of criminal/violent activity in small cities to spatio-temporally distributed, decentralized outbursts of activity in large cities, indicating that in order to maintain peace, bigger cities need larger ratio of law enforcement officers than smaller cities. We also observe existence of tipping points for communities of all sizes in the model: reducing the number of law enforcement officers below a critical level can rapidly increase the incidence of criminal/violent activity. Though surprising, these trends are in agreement with the data. ags@man.ac.uk (Alistair Sutcliffe and Di Wang) Article http://jasss.soc.surrey.ac.uk/15/1/3.html http://jasss.soc.surrey.ac.uk/15/1/3.html Wed, 01 Feb 2012 12:54:00 +0000 Alistair Sutcliffe and Di Wang: A computational model for the development of social relationships is described. The model implements agent strategies for social interaction based on Dunbar's Social Brain Hypothesis (SBH). A trust related process controls the formation and decay of relationships as a function of interaction frequency, the history of interaction, and the agents' strategies. A good fit the SBH predictions was found across a range of model parameter settings, which varied the waning rate of trust, defect/cooperation rates for agents, and linear/log functions for trust increase and decay. Social interaction strategies which favour interacting with existing strong ties or a time variant strategy produced more SBH conformant results than strategies favour more weaker relationships. The prospects for modeling the emergence of social relationships are discussed. julia.schindler@uni-bonn.de (Julia Schindler) Article http://jasss.soc.surrey.ac.uk/15/1/4.html http://jasss.soc.surrey.ac.uk/15/1/4.html Wed, 01 Feb 2012 12:53:00 +0000 Julia Schindler: In current research there is increasing evidence on why and how common-pool resources are successfully, i.e. sustainably, managed without the force of (often unsuccessful) top-level policy regulations. G. Hardin argued in 1968 in his Tragedy of the Commons (Hardin 1968) that commons must become depleted if users are free to choose extraction and resource use levels. In this study, we propose that socio-psychological factors can explain the success of resource use of a common without any top-level regulations. We exemplify this behavior by a spatio-temporally dynamic agent-based model of the Tragedy of the Commons using behavioral game theory and Nash equilibria calculation. By providing a spatio-temporal representation of Hardin's dilemma, the model could verify his argument in a temporal way if socio-psychological influence is disregarded, and indicated that under its influence the common can be sustained. We illustrated how dispositions such as cooperativeness, positive reciprocity, fairness towards others, and risk aversion broadly can support sustainable use, while negative reciprocity, fairness towards oneself, and conformity can inhibit it. Though, we also showed that it would be dangerous to generalize this kind of behavior, as changes in one of these dispositions can result in opposite system behavior, in dependence on the other dispositions. Due to this general capacity to account for such complex behavior that real common-pool system usually exhibit, and its ability to model intermediate equilibria, the proposed modelling approach, i.e. combining game-theory solution concepts with agent-based modelling, may be worth an assessment of its capacity to model empirical phenomena. g.cerulli@ceris.cnr.it (Giovanni Cerulli) Article http://jasss.soc.surrey.ac.uk/15/1/7.html http://jasss.soc.surrey.ac.uk/15/1/7.html Wed, 01 Feb 2012 12:52:00 +0000 Giovanni Cerulli: By means of a simulated funding-agency/supported-firm stochastic dynamic game, this paper shows that the level of the subsidy provided by a funding (public) agency, normally used to correct for firm R&D shortage, might be severely underprovided. This is due to the "externalities" generated by the agency-firm strategic relationship, as showed by comparing two versions of the model: one assuming "rival" behaviors between companies and agency (i.e., the current setting), and one associated to the "cooperative" strategy (i.e. the optimal Pareto-efficient benchmark). The paper looks also at what "welfare" implications are associated to different degrees of persistency in the funding effect on corporate R&D. Three main conclusions are thus drawn: (i) the relative quota of the subsidy to R&D is undersized in the rival compared to the cooperative model; (ii) the rivalry strategy generates distortions that favor the agency compared to firms; (iii) when passing from less persistent to more persistent R&D additionality/crowding-out effect, the lower the distortion the greater the variance is and vice versa. As for the management of R&D funding policies, we suggest that all the elements favouring greater collaboration between agency and firm objectives may help current R&D support to approach its social optimum. james.nolan@usask.ca (Adam Arsenault, James Nolan, Richard Schoney and Donald Gilchrist) Article http://jasss.soc.surrey.ac.uk/15/1/11.html http://jasss.soc.surrey.ac.uk/15/1/11.html Wed, 01 Feb 2012 12:51:00 +0000 Adam Arsenault, James Nolan, Richard Schoney and Donald Gilchrist: Land acquisition and ownership is an important part of modern agriculture in North America. Given the unique nature of farmland as a good, this paper develops a multi-agent simulation of farmland auction markets in a Canadian context. The model is used to generate data on land transactions between farm agents to determine if a particular auction design or type is better suited to farmland transactions. The simulation uses three different sealed-bid auctions, as well as an English auction. The auctions are compared on the basis of efficiency, stability, and perceived surplus. We find that the form of agent learning about land markets affects both sale price and the variance of sale prices in all of the studied auctions. The second-price-sealed-bid auction generates the most perceived surplus, most equitable share of surplus, and also decreases uncertainty in the common-value element of prices. But on a macroscopic level, it appears that auction choice does not influence market structure or evolution over time. sanmay@gmail.com (Teruhiko Yoneyama, Sanmay Das and Mukkai Krishnamoorthy) Article http://jasss.soc.surrey.ac.uk/15/1/5.html http://jasss.soc.surrey.ac.uk/15/1/5.html Wed, 01 Feb 2012 12:50:00 +0000 Teruhiko Yoneyama, Sanmay Das and Mukkai Krishnamoorthy: Pandemics can cause immense disruption and damage to communities and societies. Thus far, modeling of pandemics has focused on either large-scale differential equation models like the SIR and the SEIR models, or detailed micro-level simulations, which are harder to apply at a global scale. This paper introduces a hybrid model for pandemics that considers both global and local spread of infection. We hypothesize that the spread of an infectious disease between regions is significantly influenced by global traffic patterns and that the spread within a region is influenced by local conditions. Thus we model the spread of pandemics considering the connections between regions for the global spread of infection and population density based on the SEIR model for the local spread of infection. We validate our hybrid model by carrying out a simulation study for the spread of the SARS pandemic of 2002-2003 using available data on population, population density, and traffic networks between different regions. While it is well-known that international relationships and global traffic patterns significantly influence the spread of pandemics, our results show that integrating these factors into relatively simple models can greatly improve the results of modeling disease spread. bersini@ulb.ac.be (Hugues Bersini) Article http://jasss.soc.surrey.ac.uk/15/1/9.html http://jasss.soc.surrey.ac.uk/15/1/9.html Wed, 01 Feb 2012 12:49:00 +0000 Hugues Bersini: Although the majority of researchers interested in ABM increasingly agree that the most natural way to program their models is to adopt OO practices, UML diagrams are still largely absent from their publications. In the last 15 years, the use of UML has risen constantly, to the point where UML has become the de facto standard for graphical visualization of software development. UML and its 13 diagrams has many universally accepted virtues. Most importantly, UML provides a level of abstraction higher than that offered by OO programming languages (Java, C++, Python, .Net ...). This abstraction layer encourages researchers to spend more time on modeling rather than on programming. This paper initially presents the four most common UML diagrams - class, sequence, state and activity diagrams (based on my personal experience, these are the most useful diagrams for ABM development). The most important features of these diagrams are discussed, and explanations based on conceptual pieces often found in ABM models are given of how best to use the diagrams. Subsequently, some very well known and classical ABM models such as the Schelling segregation model, the spatial evolutionary game, and a continuous double action free market are subjected to more detailed UML analysis. dignum@cs.uu.nl (Frank Dignum) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/3.html http://jasss.soc.surrey.ac.uk/15/1/reviews/3.html Wed, 01 Feb 2012 12:48:00 +0000 Review of: Heuristics: The Foundations of Adaptive Behavior by Gigerenzer, Gerd, Hertwig, Ralph and Pachur, Thorsten (eds.), reviewed by Frank Dignum c.elsenbroich@surrey.ac.uk (Corinna Elsenbroich) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/4.html http://jasss.soc.surrey.ac.uk/15/1/reviews/4.html Wed, 01 Feb 2012 12:47:00 +0000 Review of: Thought Experiments in Methodological and Historical Contexts (History of Science and Medicine Library: Medieval and Early Modern Science 15) by Ierodiakonou, Katerina and Roux, Sophie (eds.), reviewed by Corinna Elsenbroich manfred.paier@arcs.ac.at (Manfred Paier) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/6.html http://jasss.soc.surrey.ac.uk/15/1/reviews/6.html Wed, 01 Feb 2012 12:46:00 +0000 Review of: Handbook on the Economic Complexity of Technological Change by Antonelli, Cristiano (ed.), reviewed by Manfred Paier tmetzler@okcu.edu (Ted Metzler) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/1.html http://jasss.soc.surrey.ac.uk/15/1/reviews/1.html Wed, 01 Feb 2012 12:45:00 +0000 Review of: The Fair Society: The Science of Human Nature and the Pursuit of Social Justice by Corning, Peter, reviewed by Ted Metzler e.j.l.chappin@tudelft.nl (Emile Chappin) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/5.html http://jasss.soc.surrey.ac.uk/15/1/reviews/5.html Wed, 01 Feb 2012 12:44:00 +0000 Review of: Phase Transitions (Primers in Complex Systems) by Sole, Ricard V., reviewed by Emile Chappin adamw@pjwstk.edu.pl (Adam Wierzbicki) Review http://jasss.soc.surrey.ac.uk/15/1/reviews/2.html http://jasss.soc.surrey.ac.uk/15/1/reviews/2.html Wed, 01 Feb 2012 12:43:00 +0000 Review of: Behavior Dynamics in Media-Sharing Social Networks by Zhao, H. Vicky, Lin, W. Sabrina and Liu, K. J. Ray, reviewed by Adam Wierzbicki