FEARLUS Publications

J.G. Polhill, N.M. Gotts and A.N.R. Law (2001)
Imitative Versus Non-Imitative Strategies in a Land Use Simulation
Cybernetics and Systems 32(1-2) 285-307.

This article describes results from a simulation model of rural land use, focusing on how the relative advantages of imitative and nonimitative approaches to land use selection change under different circumstances. It is shown that the success of "imitation" depends in quite complex ways on the type of imitation used, the strategies of other agents with which the imitator is interacting, and aspects of the heterogeneity of the environment.

J.G. Polhill, N.M. Gotts and A.N.R. Law (2002)
Combining Object-Oriented Programming and Relational Databases for Multi-Scale Spatially-Integrated Agent-Based Models
In Rizzoli, A.E. and Jakeman, A.J. (eds) Integrated Assessment and Decision Support. Proceedings of the 1st biennial meeting of the International Environmental Modelling and Software Society Vol.2, pp.251-256.

Object-oriented (OO) programming has limitations when used to implement abstract multi-scale, spatially-integrated, agent-based models, that could potentially be addressed using relational databases (RDB). Although this would involve rethinking the approach to designing such models, the combined OO-RDB approach has a number of appealing advantages for multi-scale simulation, such as allowing the user rather than the programmer to specify the scale at which various land-use processes take place. It also provides a basis for a more realistic representation of the relationship between agents and their environment.

N.M. Gotts, J.G. Polhill and A.N.R. Law (2003)
Agent-Based Simulation In The Study Of Social Dilemmas
Artificial Intelligence Review 19(1) 3-92.

This review discusses agent-based social simulation (ABSS) in relation to the study of social dilemmas such as the Prisoner's Dilemma and Tragedy of the Commons. Its aims are to explore the place of ABSS in relation to other research methods such as mathematical analysis, to familiarise AI researchers (particularly those working on multi-agent systems) with a body of relevant multidisciplinary work, and to suggest directions for future ABSS research on social dilemmas.

ABSS research can contribute greatly to the understanding of social phenomena, but needs to be based on a clear appreciation of the current "state of play" in the areas where it is used. With regard to "thin" (simple, general) simulation models, this primarily means attending to what has been or could be discovered by mathematical analysis, to work using other forms of simulation, and to the relevant theoretical disputes; with regard to "thick" (specific, detailed) models (about which the paper has less to say), linking to the relevant "thin" models and to the empirical evidence. The bulk of ABSS work on social dilemmas has been concentrated in quite a narrow --- though certainly significant --- area (reciprocal altruism in the Prisoner's Dilemma), and has sometimes been seriously flawed by over-ambitious claims, and insufficient attention to analytical approaches --- although this same work has been very fertile in terms of inspiring further work, both analytical and simulation-based.

N.M. Gotts, J.G. Polhill and A.N.R. Law (Draft)
Aspiration Levels in a Land Use Simulation to appear in Cybernetics and Systems.

The paper describes experiments with FEARLUS, an agent-based model of land use change. The agents are satisficing (rather than optimising) decision-makers. The paper focuses on the effects of varying agents' aspiration threshold: the economic return an agent requires from a parcel of land to persist with the current land use. If the threshold is not reached, the agent chooses a land use at random to apply to that parcel in the next year. It is shown that the optimum level for the aspiration threshold is affected by environmental heterogeneity, and the level of return required to break even.

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C. Cioffi-Revilla and N.M. Gotts
Comparative Analysis of Agent-Based Social Simulations: GeoSim and FEARLUS models
Proceedings, International Workshop M2M: "Model to Model" Workshop on Comparing Multi-Agent Based Simulation Models, Marseille, France, March 31-April 1, 2003, pp.91-110.

In this paper we compare models of two different kinds of processes in multi-agent-based social simulations (MABSS): military conflict within a states-system (GeoSim), and land use and ownership change (FEARLUS). This is a kind of model-to-model comparison which is novel within Multi-Agent Based Simulation research, although well-known within mathematics, physics and biology: comparing objects (in this case MABSS) drawn from distinct research domains, in order to draw out their structural similarities and differences. This can facilitate research in both domains, by allowing the use of findings from each to illuminate the other. Based on the similarities between FEARLUS and GeoSim, we conclude by identifying a new class of MABSS models based on territorial resource allocation processes occurring on a 2-dimensional space (which we define as the "TRAP2" class). The existence of the cross-domain TRAP2 class of models in turn suggests that MABSS researchers should look for other members of the class, sharing some of the properties or dynamics common to the GeoSim and FEARLUS models compared in this study: a systematic comparison of a set of related models from a range of apparently distinct domains should generate insights into both MABSS modeling, and the domains concerned.

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N.M. Gotts, J.G. Polhill, A.N.R. Law and I.R. Izquierdo
Dynamics of Imitation in a Land Use Simulation
Proceedings of the AISB '03 Second International Symposium on Imitation in Animals and Artifacts, 7-11 April 2003, University of Wales, Aberystwyth, pp.39-46.

The paper concerns the socio-spatial dynamics of imitation within a computational model of land use selection and change. Specifically, it reports investigations of the success of imitation in relation to alternative ways of choosing a course of action, in the context of different degrees and kinds of spatio-temporal heterogeneity. Simulation experiments with the model are the main method employed, but analytical work is also reported.

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I.R. Izquierdo, N.M. Gotts and J.G. Polhill
FEARLUS-W: An Agent-Based Model of River Basin Land Use and Water Management
Paper presented at "Framing Land Use Dynamics: Integrating knowledge on spatial dynamics in socio-economic and environmental systems for spatial planning in western urbanized countries", International Conference 16-18 April 2003, Utrecht University, The Netherlands.

This paper describes a spatially-explicit agent-based model of river basin land use and water management. The model is being implemented within a project aimed at investigating ways of synthesising stakeholder priorities, taking the EU Water Framework Directive as a case study.

There are many human activities that take place in a river basin and can alter the ecological status of the water, and there are also many others whose outcomes depend on that ecological status. These interactions between the socio-economic and the ecological aspects of the socio-ecosystem are shaped by the spatial distribution of the situation. Water users upstream generally have an advantage over those downstream: the first chance to use (and perhaps abstract or pollute) the water. The flowing nature of water creates asymmetries in the interactions between users. FEARLUS-W is a spatially-explicit agent-based model built to increase our understanding of these complex interactions and explore how common-pool resource problems in river basin management might be tamed through socio-economic interactions between stakeholders (primarily rural land managers), and through management strategies aimed at shaping these interactions.

FEARLUS-W is being constructed within an extended version of an existing spatially-explicit agent-based model of land use change, FEARLUS (Polhill, Gotts and Law, 2001), drawing on theories of common-pool resource use, and on survey work among stakeholders. The main extensions to FEARLUS deal with water, water flow and water pollution on the one hand and allow for agents with multiple and potentially conflicting top-level goals on the other.

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