Technical Reports

The ICICS/CS Reading Room

UBC CS TR-2001-09 Summary

Constraint-Based Agents: A Formal Model for Agent Design, May 25, 2001 Alan K. Mackworth and Ying Zhang, 20 pages

Formal models for agent design are important for both practical and theoretical reasons. The Constraint-Based Agent (CBA) model includes a set of tools and methods for specifying, designing, simulating, building, verifying, optimizing, learning and debugging controllers for agents embedded in an active environment. The agent and the environment are modelled symmetrically as, possibly hybrid, dynamical systems in Constraint Nets. This paper is an integrated presentation of the development and application of the CBA framework, emphasizing the important special case where the agent is an online constraint-satisfying device. Using formal modeling and specification, it is often possible to verify complex agents as obeying real-time temporal constraint specifications and, sometimes, to synthesize controllers automatically. In this paper, we take an engineering point of view, using requirements specification and system verification as measurement tools for intelligent systems. Since most intelligent systems are real-time dynamic systems, the requirements specification must be able to represent timed properties. We have developed timed $\forall$-automata for this purpose. We present this formal specification, examples of specifying requirements and a general procedure for verification. The CBA model demonstrates the power of viewing constraint programming as the creation of online constraint-solvers for dynamic constraints.

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