Abteilung Wissensbasierte Systeme Heterogeneous Active Agents, Iii: Polynomially Implementable Agents

In (Eiter, Subrahmanian, and Pick 1999), the authors have introduced techniques to build agents on top of arbitrary data structures, and to “agentize” new/existing programs. They provided a series of successively more sophisticated semantics for such agent systems, and showed that as these semantics become epistemically more desirable, a computational price may need to be paid. In this paper, we identify a class of agents that are called weak regular—this is done by first identifying a fragment of agent programs (Eiter, Subrahmanian, and Pick 1999) called weak regular agent programs (WRAPs for short). It is shown that WRAPs are definable via three parameters—checking for a property called “safety”, checking for a property called “conflict freedom” and checking for a “deontic stratifiability” property. Algorithms for each of these are developed. A weak regular agent is then defined in terms of these concepts , and a regular agent is one that satisfies an additional “boundedness” property. We then describe a polynomial algorithm that computes (under suitable assumptions) the “reasonable status set” semantics of regular agents—this semantics was identified in (Eiter, Subrahmanian, and Pick 1999) as being epistemically most desirable. Though this semantics is co-NP-complete for arbitrary agent programs, it is polynomially computable via our algorithm for regular agents. Finally, we describe our implementation architecture and provide details of how we have implemented RAPs, together with experimental results. 1Institut und Ludwig Wittgenstein Labor für Informationssysteme, Technische Universität Wien, Paniglgasse 16, A-1040 Wien, Austria. E-mail: [email protected] 2Institute for Advanced Computer Studies, Institute for Systems Research and Department of Computer Science, University of Maryland, College Park, Maryland 20742. E-mail: [email protected] 3Institute for Advanced Computer Studies, Department of Computer Science, University of Maryland, College Park, Maryland 20742. E-mail: [email protected] Acknowledgements: We would like to thank Anatoly Levkov, Rob Ross, and Mustafa Tikir for writing code to implement some algorithms defined in this paper. We have benefited from discussions with Juergen Dix, Bob Kowalski, and Sarit Kraus. This work was supported by the Army Research Office under Grants DAAH-04-95-10174, DAAH-04-9610297, and DAAH04-96-1-0398, by the Army Research Laboratory under contract number DAAL01-97K0135, by an NSF Young Investigator award IRI-93-57756, by a DAAD grant, and by the Austrian Science Fund Project N Z29-INF. This is Part III which extends Technical Reports INFSYS TR 1843-9802 and 1843-9803 “Heterogeneous Active Agents”. Copyright c 1999 by the authors INFSYS RR 1843-99-07 I