The National Institute for Mathematical and Biological Synthesis (NIMBioS) is now accepting applications for the NIMBioS sponsored Investigative Workshop on agent-based modeling, to be held December 1-3, 2009 at NIMBioS.

*Topic: Optimal Control and Optimization for Individual-based and Agent-based Models

*Organizers: Filippo Castiglione, Institute for Computing Applications, Rome;
Volker Grimm, UFZ Center for Environmental Research, Leipzig; Reinhard Laubenbacher, Virginia Bioinformatics Institute; Suzanne Lenhart, University of Tennessee.

*Location: NIMBioS at the University of Tennessee, Knoxville

*Objectives: Agent-based models are used increasingly to understand a broad range of biological phenomena, including, e.g., tumor growth, the immune system, and the spread of infectious diseases across social networks. In all these cases it would be very useful to have analytic methods available to study in general how possible interventions would affect system dynamics. The advantage of agent-based models is that they integrate local relationships to capture global emergent dynamics, without needing global parameters as input. The disadvantage of this type of model is that very few mathematical analysis methods are available to produce general descriptions of model response particularly in terms of spatio-temporal patterns arising from even fairly simple ABMs. In particular, the absence of a state space description of ABMs makes it very difficult to apply available control theory methods to study effective interventions. Applications of ABMs in situations with possible interventions by human actions (e.g., vaccination and quarantine schemes) have usually been limited to scenario analyses. In this case the models are simulated numerous times to compare alternative scenarios for intervention.

One possible approach to this problem is to construct state space models that approximate the agent-based model, similar to approaches proposed for discrete event simulations. This uses system identification methods developed for the state space model framework for agent-based simulations. Control-theoretic approaches for this modeling framework have been explored in a few cases. A first exploratory project in this direction resulted in a control method for in vitro competition of viruses. Such methods from approximate models may not work when there is spatial heterogeneity in the agent-based model (Federico, Gross and Lenhart, in preparation). Various techniques from optimal control and discrete optimization should be considered to investigate alternative formulations of control in relation to a state-space approximation and then compared to a similar formulation applied to the ABM.

This workshop brings together researchers working in agent-based models, optimal control and optimization to discuss the possible development of control theoretic approaches for agent-based models, beginning with the ones mentioned above. Alternative formulations of the approximation models and optimal control/optimization methods appropriate to each formulation will be considered.

*Application deadline: October 1, 2009

For more information about the workshop and a link to the online application form, go to http://www.nimbios.org/announcements/WS_OptimalControl.html

NIMBioS Investigative Workshops involve 30-40 participants, focus on a broad topic or a set of related topics, attempt to summarize/synthesize the state of the art and identify future directions, and have potential for leading to one or more future Working Groups . Participation is open (but numbers are limited), so individuals with a strong interest in the topic are encouraged to apply. Post-docs and graduate students are eligible to apply. If needed, NIMBioS can provide support (travel, meals, lodging) for Workshop attendees.

For more information, e-mail AgentBasedModels@nimbios.org