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The AGENTS system is a set of programs designed to generate automatically the mask-level layout of full custom CMOS, BICMOS, and bipolar leaf cells. The system is formed from four sever programs: the placer, router, database, and broker. The placer places components in a cell, the router wires the circuits sent to it, the database stores all the information that is dependent upon the fabrication process, such as the design rules, and the Broker makes the services of the other servers available. These servers communicate over a computer network using the TCP/IP Internet Protocol. The Placer server receives from its client the description and netlist of the circuit to be generated using EDIF (Electronic Design Interchange Format.) The output to its client is the mask layout of the circuit, again codified in EDIF. The comcept of agents as software components which have the ability to communicate and cooperate with each other is at the heart of the AGENTS system. This concept is not only used at the higher level, for the four servers, but at a lower level as well, inside the Router and Placer servers, where small relatively simple agents work together to accomplish complex tasks. These small agents are responsible for all the reasoning carried out by the two servers, as they hold the basic inference routines and the knowledge needed by the servers. The system's philosophy is that competence should emerge out of the collective behavior of a large number of relatively simple agents. In addition and integrated to these small agents, the system uses a genetic algorithm to improve components' placement before routing.