A resolution principle for clauses with constraints

We introduce a general scheme for handling clauses whose variables are constrained by an underlying constraint theory. In general, constraints can be seen as quantifier restrictions as they filter out the values that can be assigned to the variables of a clause (or an arbitrary formulae with restricted universal or existential quantifier) in any of the models of the constraint theory. We present a resolution principle for clauses with constraints, where unification is replaced by testing constraints for satisfiability over the constraint theory. We show that this constrained resolution is sound and complete in that a set of clauses with constraints is unsatisfiable over the constraint theory if we can deduce a constrained empty clause for each model of the constraint theory, such that the empty clauses constraint is satisfiable in that model. We show also that we cannot require a better result in general, but we discuss certain tractable cases, where we need at most finitely many such empty clauses or even better only one of them as it is known in classical resolution, sorted resolution or resolution with theory unification

On abduction and answer generation through constrained resolution

Recently, extensions of constrained logic programming and constrained resolution for theorem proving have been introduced, that consider constraints, which are interpreted under an open world assumption. We discuss relationships between applications of these approaches for query answering in knowledge base systems on the one hand and abduction-based hypothetical reasoning on the other hand. We show both that constrained resolution can be used as an operationalization of (some limited form of) abduction and that abduction is the logical status of an answer generation process through constrained resolution, ie., it is an abductive but not a deductive form of reasoning

Reasoning about temporal relations : a maximal tractable subclass of Allen\u27s interval algebra

We introduce a new subclass of Allen\u27s interval algebra we call "ORD-Horn subclass", which is a strict superset of the "pointisable subclass". We prove that reasoning in the ORD-Horn subclass is a polynomial-time problem and show that the path-consistency method is sufficient for deciding satisfiability. Further, using an extensive machine-generated case analysis, we show that the ORD-Horn subclass is a maximal tractable subclass of the full algebra (assuming P neq NP). In fact, it is the unique greatest tractable subclass amongst the subclasses that contain all basic relations

TeleTruck : a holonic fleet management system

In this paper we describe TeleTruck, a multiagent dispatching system that was developed in close cooperation with a forwarding company and that is capable of handling real-world requirements like dynamics and uncertainty. The main idea underlying the TeleTruck approach is the usage of holonic agents, i.e. agents composed of subagents that act in a corporated way. We describe the implementation in detail and point out the advantages of the holonic paradigm

An intercompany dispatch support system for intermodal transport chains

A critical problem in an intermodal transport chain is the direct meet at the transhipment nodes. This requires information technology and modern communication facilities as well as much closer collaboration between all the concerned transport operators in the chain. The TELETRUCK system - currently under development at the German Research Center for Artificial Intelligence (Deutsches Forschungszentrum für Künstliche Intelligenz DFKI GmbH) - is a dispatch support system that tackles those problems. Intercompany planning, scheduling, and monitoring of intermodal transport chains will be supported by our system. It aims at providing smooth access to railway time tables and rail-based transport services and - much more important - at allowing for the planning of both, exclusively road-based and combined journeys and showing their cost-effectiveness, where- and whenever possible. We will describe our approach - based on intelligent agent technology - both the current state of implementation and our goal of the very next future

Reasoning about temporal relations : a maximal tractable subclass of Allen's interval algebra

We introduce a new subclass of Allen's interval algebra we call "ORD-Horn subclass", which is a strict superset of the "pointisable subclass". We prove that reasoning in the ORD-Horn subclass is a polynomial-time problem and show that the path-consistency method is sufficient for deciding satisfiability. Further, using an extensive machine-generated case analysis, we show that the ORD-Horn subclass is a maximal tractable subclass of the full algebra (assuming P neq NP). In fact, it is the unique greatest tractable subclass amongst the subclasses that contain all basic relations

Simulated Trading Mechanismen für speditionsübergreifende Transportplanung

In den letzten Jahren hat sich der Konkurrenzdruck, unter dem die kleinen und mittleren Unternehmen der deutschen Speditionsbranche stehen, maßgeblich verschärft. Eine Möglichkeit, diesem Druck zu begegnen, ist die Bildung von Speditionsverbünden, sozusagen virtuellen Transportunternehmen, die in der Lage sind, durch kooperative Disposition, ihre Wettbewerbsfähigkeit zu erhöhen. In diesem Papier stellen wir einen Agentenbasierten Ansatz zur IT Unterstützung der Unternehmensabläufe, insbesondere der Transportoptimierung, in einem solchen virtuellen Transportunternehmen vor. Der verteilte, marktbasierte Simulated Trading Optimierungsmechanismus liefert gute Ergebnisse in kooperativen Multiagenten-Planungsszenarien. Wir haben den Mechanismus um die Möglichkeit des expliziten, monetären Nutzentransfers zwischen den Beteiligten Agenten ergänzt. Somit können wir auch in kompetitiven Domänen effiziente Transportoptimierung vornehmen.Within the past few years the pressure of competition, to which the small and medium sized enterprises of the European transportation industry are exposed, sharpened significantly. One opportunity to withstand this pressure is to form cooperative networks of transportation companies. These kinds of virtual transportation enterprises are able to improve their competitiveness by co-operative transportation planning. In this paper we present an agent-based approach for the IT support of business processes in virtual transportation enterprises. We mainly focus on co-operative optimization of transportation planning. The distributed, market-based Simulated Trading algorithm is well suited in co-operative multi-agent planning domains. We have extended the mechanism with explicit monetary utility transfer between the participating agents. This allow to apply the Simulated Trading mechanism in competitive transportation scenarios in order to improve the planning efficiency

RATMAN and its relation to other multi-agent testbeds

RATMAN (Rational Agents Testbed for Multi Agent Networks) is a workbench for the definition and testing of rational agents in multiagent environments. The special feature of RATMAN is the specification of such agents with hierarchical knowledge bases comprising all knowledge levels from sensoric knowledge to learning capabilities. In all levels only knowledge representation languages have to be used which are based on logic. On each knowledge level the designer may choose the granularity of knowledge for the agent to be designed and moreover he may decide whether the agent should have a certain skill at all. Thus it will be possible to construct a society of very heterogeneous agents from expert systems on one side of the spectrum to simple reactive agents on the other side. Since the aim of such a testbed is to get more insight in the behavior of intelligent agents'; cooperating actions, RATMAN is providing a set of statistical and documentational features. In the second part other approaches to multiagents environments are presented. AF, MACE, AGORA and MAGES are first characterized by their main features. Then their specialities are discussed and finally the boarders with respect to RATMAN are considered

TeleTruck : a holonic fleet management system

In this paper we describe TeleTruck, a multiagent dispatching system that was developed in close cooperation with a forwarding company and that is capable of handling real-world requirements like dynamics and uncertainty. The main idea underlying the TeleTruck approach is the usage of holonic agents, i.e. agents composed of subagents that act in a corporated way. We describe the implementation in detail and point out the advantages of the holonic paradigm