Zhisheng Huang

The BOID architecture: conflicts between beliefs, obligations, intentions and desires

In this paper we introduce the so-called Beliefs-Obligations-Intentions-Desires or BOID architecture. It contains feedback loops to consider all effects of actions before committing to them, and mechanisms to resolve conflicts between the outputs of its four components. Agent types such as realistic or social agents correspond to specific types of conflict resolution embedded in the BOID archecture.

Debugging Incoherent Terminologies

In this paper we study the diagnosis and repair of incoherent terminologies. We define a number of new nonstandard reasoning services to explain incoherence through pinpointing, and we present algorithms for all of these services. For one of the core tasks of debugging, the calculation of minimal unsatisfiability preserving subterminologies, we developed two different algorithms, one implementing a bottom-up approach using support of an external description logic reasoner, the other implementing a specialized tableau-based calculus. Both algorithms have been prototypically implemented. We study the effectiveness of our algorithms in two ways: we present a realistic case study where we diagnose a terminology used in a practical application, and we perform controlled benchmark experiments to get a better understanding of the computational properties of our algorithms in particular and the debugging problem in general.

MultimediaN e-culture demonstrator

The main objective of the MultimediaN E-Culture project is to demonstrate how novel semantic-web and presentation technologies can be deployed to provide better indexing and search support within large virtual collections of cultural-heritage resources. The architecture is fully based on open web standards, in particular XML, SVG, RDF/OWL and SPARQL. One basic hypothesis underlying this work is that the use of explicit background knowledge in the form of ontologies/vocabularies/thesauri is in particular useful in information retrieval in knowledge-rich domains.

Dynamic Goal Hierarchies

In this paper we introduce and formalise dynamic goal hierarchies. We begin with a formal definition of goals, according to which they are rational desires. In particular, we require that an agents goals are coherent; that is, that the agent believes that each goal is jointly realisable with all of the goals which the agent considers to be more important. Thus an agents goals form a hierarchy, and new goals are defined with reference to it. We then show how preferential entailment can be used to formalise the rational revision of goals and goal hierarchies.

Reasoning with multi-version ontologies: a temporal logic approach

In this paper we propose a framework for reasoning with multi-version ontology, in which a temporal logic is developed to serve as its semantic foundation. We show that the temporal logic approach can provide a solid semantic foundation which can support various requirements on multi-version ontology reasoning. We have implemented the prototype of MORE (Multi-version Ontology REasoner), which is based on the proposed framework. We have tested MORE with several realistic ontologies. In this paper, we also discuss the implementation issues and report the experiments with MORE.

STEP: a Scripting Language for Embodied Agents

In this chapter we propose a scripting language, called STEP, for embodied agents, in particular for their communicative acts like gestures and postures. Based on the formal semantics of dynamic logic, STEP has a solid semantic foundation, in spite of a rich number of variants of the compositional operators and interaction facilities on worlds. STEP has been implemented in the distributed logic programming language DLP, a tool for the implementation of 3D web agents. In this chapter, we discuss principles of scripting language design for embodied agents and several aspects of the application of STEP.

A Kernel Revision Operator for Terminologies -- Algorithms and Evaluation

Revision of a description logic-based ontology deals with the problem of incorporating newly received information consistently. In this paper, we propose a general operator for revising terminologies in description logic-based ontologies. Our revision operator relies on a reformulation of the kernel contraction operator in belief revision. We first define our revision operator for terminologies and show that it satisfies some desirable logical properties. Second, two algorithms are developed to instantiate the revision operator. Since in general, these two algorithms are computationally too hard, we propose a third algorithm as a more efficient alternative. We implemented the algorithms and provide evaluation results on their efficiency, effectiveness and meaningfulness in the context of two application scenarios: Incremental ontology learning and mapping revision.

Swi-prolog and the web

Prolog is an excellent tool for representing and manipulating data written in formal languages as well as natural language. Its safe semantics and automatic memory management make it a prime candidate for programming robust Web services. Although Prolog is commonly seen as a component in a Web application that is either embedded or communicates using a proprietary protocol, we propose an architecture where Prolog communicates to other components in a Web application using the standard HTTP protocol. By avoiding embedding in external Web servers, development and deployment become much easier. To support this architecture, in addition to the transfer protocol, we must also support parsing, representing and generating the key Web document types such as HTML, XML and RDF. This article motivates the design decisions in the libraries and extensions to Prolog for handling Web documents and protocols. The design has been guided by the requirement to handle large documents efficiently. The described libraries support a wide range of Web applications ranging from HTML and XML documents to Semantic Web RDF processing. The benefits of using Prolog for Web-related tasks are illustrated using three case studies.

Implementation of a scripting language for VRML/X3D-based embodied agents

Embodied agents or humanoid avatars may effectively be used to communicate with human users. Currently there is a wide range of specification formalisms and scripting languages for embodied agents, many of which are of a somewhat ad hoc nature lacking clear semantics. In this paper, we discuss the implementation of a scripting language for humanoid avatars in VRML/X3D-based environments. The scripting language STEP is based on dynamic logic, which provides a clear semantics for complex behavioral patterns. Moreover, the implementation of STEP is realized in a platform that extends VRML/X3D with distributed logic programming (DLP), which provides the computational support necessary to realize such complex behavioral patterns as well as the interaction with a (rich media) 3D environment. As an application example, we will discuss the development of an instructional VR for Tai Chi (the Chinese art of movement), illustrating how our approach allows for the creation of reusable libraries of behavioral patterns. We will discuss some implementation issues, in particular how to realize parallel actions and synchronization within an environment.

ALX, an action logic for agents with bounded rationality

Abstract We propose a modal action logic that combines ideas from H.A. Simons bounded rationality, S. Kripkes possible world semantics, G.H. von Wrights preference logic, Pratts dynamic logic, Stalnakers minimal change and more recent approaches to update semantics. ALX (the xth action logic) is sound, complete and decidable, making it the first complete logic for two-place preference operators. ALX avoids important drawbacks of other action logics, especially the counterintuitive necessitation rule for goals (every theorem must be a goal) and the equally counterintuitive closure of goals under logical implication.