Software Review: NetLogo, a Multi-agent Simulation Environment

NetLogo [41, 40] is a freely downloadable, agent-based software package that was created at the Center for Connected Learning and Computer-Based Modeling (CCL) at Northwestern University, directed by Uri Wilensky. It is the latest in a series of multi-agent simulation environments that includes StarLogo [28, 33], which was developed at the MIT Media Lab by Wilensky and Mitchel Resnick. In these environments, agents are represented as ‘‘turtles’’ and are programmed with a variant of Seymour Papert’s LOGO [8, 19]. Designed to be simple enough for children to program, NetLogo illustrates what can happen when populations of turtles are given sets of rules to obey. Despite the entry-level programming interface, NetLogo is capable of quite sophisticated modeling and allows experienced programmers to add their own Java extensions. As a result, NetLogo has been widely used by a broad audience, from elementary school children to academics in the social, computer, and ‘‘hard’’ sciences; and the on-line community page includes models constructed by a wide range of representatives from each of these segments of the population. The NetLogo home page (http://ccl.northwestern.edu/netlogo/) includes a download area, models pages, sample downloadable extensions, user manuals, a FAQ, and links to various resources. The software package comes with a large number of demonstration models, each of which can be executed and modified, since the source for each demo is included in the package. These demos are also available on the ‘‘models’’ portion of the home page, where they can be run in a Web browser. They are contributed by community members and are tested and supported by the development team at CCL. Model application areas range from biology to computer science to art to artificial life and include simulations such as predator-prey, spread of disease, rumor mill, traffic jams, small worlds, fractals, erosion, dining philosophers, cellular automata, crystallization, and radioactivity. In addition, on the ‘‘community models’’ portion of the home page, an even larger and more diverse set of models is available. These, too, have been contributed by community members, but they are not checked by CCL staff; they are supported by their authors, whose contact details are listed on the Web page. NetLogo was first released in 1999, and the most recent release (as of this writing) is version 3.1.2 (August 9, 2006). NetLogo runs on virtually any of today’s most popular platforms—Microsoft Windows, Mac OS-X, and Linux. For each version released, the Web page (URL) enumerates the operating systems on which NetLogo has been successfully installed and executed. NetLogo is written in Java, which aids its portability and compatibility. One of the most convenient features of NetLogo allows programmers to save models as Java applets, permitting seamless publication of simulations from NetLogo’s built-in integrated development environment to a Web page.