Wyniki wyszukiwania - Biblioteka Nauki

1

A Tuning Machine for Cooperative Problem Solving

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Dunin-Kęplicz B. , Verbrugge R.

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2004

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tom Vol. 63, nr 2,3

283--307

EN

In this paper we aim to formally model individual, social and collective motivational attitudes in teams of agents involved in Cooperative Problem Solving. Particular attention is given to the strongest motivational attitude, collective commitment, which leads to team action. First, building on our previous work, a logical framework is sketched in which social commitments and collective intentions are formalized. Then, different versions of collective commitments are given, reflecting different aspects of Cooperative Problem Solving, and applicable in different situations. The definitions differ with respect to the aspects of teamwork of which the agents involved are aware, and the kind of awareness present within a team. In this way a kind of tuning mechanism is provided for the system developer to tune a version of collective commitment fitting the circumstances. Finally, we focus attention on a few exemplar versions of collective commitment resulting from instantiating the general tuning scheme, and sketch for which kinds of organization and application domains they are appropriate.

2

Collective Intentions

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Dunin-Kęplicz B. , Verbrugge R.

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2002

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tom Vol. 51, nr 3

271-295

EN

In this paper the notion of collective intention in teams of agents involved in cooperative problem solving (CPS) in multiagent systems (MAS) is investigated. Starting from individual intentions, goals, and beliefs defining agents' local asocial motivational and informational attitudes, we arrive at an understanding of collective intention in cooperative teams. The presented definitions are rather strong, in particular a collective intention implies that all members intend for all others to share that intention. Thus a team is created on the basis of collective intention, and exists as long as this attitude between team members exists, after which the group may disintegrate. For this reason it is crucial that collective intention lasts long enough. Collective intentions are formalized in a multi-modal logical framework. Completeness of this logic with respect to an appropriate class of Kripke models is proved. Two versions of collective intentions are discussed in the context of different situations. It is assumed that these definitions reflect solely vital aspects of motivational attitudes, leaving room for case-specific extensions. This makes the framework flexible and not overloaded. Together with individual and collective knowledge and belief, collective intention constitutes a basis for preparing a plan, reflected in the strongest attitude, i.e., in collective commitment, defined and investigated in our other papers.

3

Evolution of Collective Commitment during Teamwork

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Dunin-Kęplicz B. , Verbrugge R.

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2003

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tom Vol. 56, nr 4

329-371

EN

In this paper we aim to describe dynamic aspects of social and collective attitudes in teams of agents involved in Cooperative Problem Solving (CPS). Particular attention is given to the strongest motivational attitude, collective commitment, and its evolution during team action. First, building on our previous work, a logical framework is sketched in which a number of relevant social and collective attitudes is formalized, leading to the plan-based definition of collective commitments. Moreover, a dynamic logic component is added to this framework in order to capture the effects of the complex actions that are involved in the consecutive stages of CPS, namely potential recognition, team formation, plan formation and team action. During team action, the collective commitment leads to the execution of agent-specific actions. A dynamic and unpredictable environment may, however, cause the failure of some of these actions, or present the agents with new opportunities. The abstract reconfiguration algorithm, presented in a previous paper, is designed to handle the re-planning needed in such situations in an efficient way. In this paper, the dynamic logic component of the logical framework addresses issues pertaining to adjustments in collective commitment during the reconfiguration process.

4

Complexity Issues in Multiagent Logics

80%

Dziubiński M. , Verbrugge R. , Dunin-Kęplicz B.

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2007

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tom Vol. 75, nr 1-4

239-262

EN

Our previous research presents a methodology of cooperative problem solving for belief-desire-intention (BDI) systems, based on a complete formal theory called TeamLog. This covers both a static part, defining individual, bilateral and collective agent attitudes, and a dynamic part, describing system reconfiguration in a dynamic, unpredictable environment. In this paper, we investigate the complexity of the satisfiability problem of the static part of TeamLog, focusing on individual and collective attitudes up to collective intention. Our logics for teamwork are squarely multi-modal, in the sense that different operators are combined and may interfere. One might expect that such a combination is much more complex than the basic multi-agent logic with one operator, but in fact we show that it is not the case: the individual part of TeamLog is PSPACE-complete, just like the single modality case. The full system, modelling a subtle interplay between individual and group attitudes, turns out to be EXPTIME-complete, and remains so even when propositional dynamic logic is added to it. Additionally we make a first step towards restricting the language of TeamLog in order to reduce its computational complexity. We study formulas with bounded modal depth and show that in case of the individual part of our logics, we obtain a reduction of the complexity to NPTIME-completeness. We also show that for group attitudes in TeamLog the satisfiability problem remains in EXPTIME-hard, even when modal depth is bounded by 2. We also study the combination of reducing modal depth and the number of propositional atoms. We show that in both cases this allows for checking the satisfiability in linear time.