Foreword
Most of the objects studied by geographers, ecologists, urban planners, economists, archaeologists – to name but a few – can be described as complex spatial systems. Such systems are composed of a large number of localised entities, interacting with one another through various networks of interaction and across different scales of space, time and aggregation. Not surprisingly, the study of complexity and its corresponding modelling and simulation tools constitute a promising approach for these disciplines. Agent-based simulations occupy a central place in such perspective, due to the variety and flexibility of investigations they allow. Once their characteristics and behaviours are defined, agents can be used to populate dynamic environments, in order to explore the conditions leading to the emergence of structures and processes in both human-dominated and natural landscapes.
The six articles in this special issue of RIG all contribute to this theme. They provide an overview of the diversity and wealth of approaches currently being undertaken in agent-based spatial simulation by researchers in different countries.
Additionally, the openness of RIG to the publication of articles in both English and French has allowed us to broaden our intellectual and cultural horizons. We take this opportunity to thank the editor-in-chief, Didier Josselin, for this excellent initiative!
The articles in this issue can be grouped according to three main themes. The first two articles illustrate the pre-requisite challenge of creating appropriately complex geographical environments suited to agent-based simulation. From the development of “virtual geographic environments” (article by Mehdi Mekni, Sébastien Paris, Bernard Moulin, Dominic Marcotte) to the constitution of
“populated urban environments” (article by Walid Chaker, Marie-Josée Proulx, Bernard Moulin et Yvan Bédard), the creation of a realistic spatial environment is extremely difficult.
The two subsequent articles provide an interesting contrast to one another, highlighting the ontological diversity of the term “spatial agent”. Thomas Louail begins with “neighbourhood” agents to simulate urban dynamics, whereas Andreas Koch makes the distinction between social agents and spatial agents, with the former taking into consideration the latter in order to adopt a strategy for residential localisation.
Lastly, the two final articles further develop the idea of interactions between social and spatial entities through the dynamic linkage of agent-based models with cellular automata. The An Ngo, Linda See and Frances Drake use this method to simulate the dynamics of changing agricultural practices in Vietnam as a function of
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384 Géomatique – 19/2009. Simulation spatiale à base d’agents
economic, social and environmental constraints. Eric Maillé, Bernard Espinasse and Sébastien Fournier simulate the dynamics of forest fire risk in peri-urban zones through the use of a model integrating multiple spatial scales.
This special issue is a clear demonstration of the significant advances that have occurred in agent-based spatial simulation since the early models. The simulated geographic environments and the agents within them are increasingly richer and more realistic, and the multiple possibilities for coupling and hybridization of different models offer promising perspectives. However, despite the inevitable increasing detail and realism of such models, we should be prudent: the degree to which we can draw conclusions about the real world from our models is directly linked to our ability to correctly use this technology and to the complexity of the systems under study. Moreover, the modelled systems will always be complex, defying precise prediction. Agent-based simulation may, however, contribute to a better understanding of the cross-scale mechanisms contributing to the emergence of structures and processes in space.
ARNAUD BANOS Géographie-Cités, CNRS/Paris 1, Paris
LAEL PARROTT Laboratoire des systèmes complexes, Université de Montréal
Département de géographie
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