Inhaltsangabe:Abstract: At present, the World Wide Web faces several problems regarding the search for specific in formation, arising, on the one hand, from the vast number of information sources available, and, on the other hand, from their intrinsic heterogeneity. A promising approach for solving the complex problems emerging in this context is the use of information agents in a multi-agent environment, which cooperatively solve advanced information-retrieval problems. An intelligent information agent provides advanced capabilities resorting to some form of logical reasoning, based on ad-hoc-knowledge about the task in question and on background knowledge of the domain, suitably represented in a knowledge base. In this thesis, our interest is in the role which some methods from the field of declarative logic programming can play in the realization of reasoning capabilities for intelligent information agents. We consider the task of updating extended logic programs (ELPs), since, in order to ensure adaptivity, an agent s knowledge base is subject to change. To this end, we develop update agents, which follow a declarative update policy and a reimplemented in the IMPACT agent environment. The proposed update agents adhere to a clear semantics and are able to deal with incomplete or in consistent information in an appropriate way. Furthermore, we introduce a framework for reasoning about evolving knowledgebases, which are represented as ELPs and maintained by an update policy. We describe a formal model which captures various update approaches, and define a logical language for expressing properties of evolving knowledge bases. We further investigate these mantical properties of knowledge states with respect to reasoning. In particular, we describe finitary characterizations of the knowledge evolution, and derive complexity results for our framework. Finally, we consider aparticular problem of information agents, namely information source selection, and develop an intelligent site-selection agent. We use ELPs for representing relevant knowledge and for declarative query an alysis and query abstraction. We define syntax and semantics of declarative site-selection programs, making use of advanced methods from answer set programming for priority handling and quantitative reasoning. A site selection component is implemented on top of the DLVKR system and its plp front-end for prioritized ELPs. We report experimental results for this implementation, [...]

These are the proceedings of the 7th International Workshop on Cooperative Information Agents (CIA 2003), held at the Sonera Conference Center in H- sinki, Finland, August 27–29, 2003. It was co-located with the 4th Agentcities Information Days. One key challenge of developing advanced agent-based information systems is to balance the autonomy of networked data and knowledge sources with the pot- tial payo? of leveraging them by the appropriate use of intelligent information agents on the Internet. An information agent is a computational software entity thathasaccesstooneormultiple,heterogeneous,anddistributeddataandinf- mation sources; proactively searches for and maintains relevant information on behalfofitshumanusersorotheragents,preferablyjust-in-time. Inotherwords, it is managing and overcoming the di?culties associated with information ov- load in the open and exponentially growing Internet and Web. Depending on the application and tasks at hand information agents may collaborate in open, n- worked data and information environments to provide added value to a variety of applications in di?erent domains. Thus, research and development of inf- mation agents is inherently interdisciplinary: It requires expertise in information retrieval, arti?cial intelligence, database systems, human-computer interaction, and Internet and Web technology. Initiated in 1997, the purpose of the annual international workshop series on cooperativeinformationagents(CIA)istoprovideaninterdisciplinaryforumfor researchers, software developers, and managers to get informed about, present, anddiscussthelatesthigh-qualityresultsinadvancementsoftheoryandpractice in information agent technology for the Internet and Web. Each event of this renowned series attempts to capture the intrinsic interdisciplinary nature of this research area by calling for contributions from di?erent research communities, and by promoting open and informative discussions on all related topics.

This book constitutes the thoroughly refereed post-proceedings of the Third International Workshop on Declarative Agent Languages and Technologies, DALT 2005, held in The Netherlands in July 2005 as an associated event of AAMAS 2005, the main international conference on autonomous agents and multi-agent systems. The 14 revised full papers presented were carefully selected during two rounds of reviewing and improvement for inclusion in the book. The papers are organized in topical sections.

This book celebratesthe 25th anniversaryof GULP—the Italian Associationfor LogicProgramming.Authored by Italian researchersat the leading edge of their ?elds, it presents an up-to-date survey of a broad collection of topics in logic programming, making it a useful reference for both researchers and students. During its 25-year existence, GULP has organised a wide range of national and international activities, including both conferences and summer schools. It has been especially active in supporting and encouraging young researchers, by providing scholarships for GULP events and awarding distinguished disser- tions. WeintheinternationallogicprogrammingcommunitylookuponGULPwith a combination of envy, admiration and gratitude. We are pleased to attend its conferences and summer schools, where we can learn about scienti?c advances, catch up with old friends and meet young students. It is an honour for me to acknowledge our appreciation to GULP for its outstanding contributions to our ?eld and to express our best wishes for its continuing prosperity in the future. March 2010 Robert Kowalski Imperial College London Preface On June 18, 1985, a group of pioneering researchers, including representatives from industry, national research labs, and academia, attended the constituent assembly of the Group of researchers and Users of Logic Programming (GULP) association. That was the starting point of a long adventure in science, that 1 we are still experiencing 25 years later. This volume celebrates this important event.

This book constitutes the refereed proceedings of the First International Workshop on Cooperative Information Agents - DAI Meets Databases, CIA-97, held in Kiel, Germany, in February 1997. The book opens with 6 invited full papers by internationally leading researchers surveying the state of the art in the area. The 16 revised full research papers presented were carefully selected during a highly competitive round of reviewing. The papers are organized in topical sections on databases and agent technology, agents for database search and knowledge discovery, communication and cooperation among information agents, and agent-based access to heterogeneous information sources.

The second edition of the workshop on Declarative Agent Languages and Te- nologies (DALT 2004) was held July 2004 in New York City, and was a great success. We saw a signi?cant increase in both the number of submitted papers and workshop attendees from the ?rst meeting, held July 2003 in Melbourne. Nearly 40 research groups worldwide were motivated to contribute to this event by submitting their most recent research achievements, covering a wide variety of the topics listed in the call for papers. More than 30 top researchers agreed to join the Program Committee, which then collectively faced the hard task of selecting the one-day event program. The fact that research in multi-agent systems is no longer only a novel and promising research horizon at dawn is, in our opinion, the main reason behind DALT’s (still short) success story. On the one hand, agent theories and app- cations are mature enough to model complex domains and scenarios, and to successfully address a wide range of multifaceted problems, thus creating the urge to make the best use of this expressive and versatile paradigm, and also pro?t from all the important results achieved so far. On the other hand, bui- ing multi-agent systems still calls for models and technologies that could ensure system predictability, accommodate ?exibility, heterogeneity and openness, and enable system veri?cation.

Declarative languages have traditionally been regarded by the mainstream c- puting community as too impractical to be put to practical use. At the same time, traditionalconferencesdevotedto declarativelanguagesdo not haveissues related to practice as their central focus. Thus, there are few forums devoted to discussion of practical aspects and implications of newly discovered results and techniques related to declarative languages. The goal of the First International Workshop on Practical Aspects of Declarative Languages (PADL) is to bring together researchers,practitioners and implementors of declarative languages to discuss practical issues and practical implications of their research results. The workshop was held in San Antonio, Texas, during January 18-19, 1999. This volume contains its proceedings. Fifty three papers were submitted in response to the call for papers. These papers were written by authors belonging to twenty one countries from six c- tinents. Each paper was assigned to at least two referees for reviewing. Twenty four papers were nally selected for presentation at the workshop. Many good papers could not be included due to the limited duration of the workshop. The workshop included invited talks by Mark Hayden of DEC/Compaq Systems - search Center, speaking on \Experiences Building Distributed Systems in ML," and Mark Wallace of Imperial College Center for Planning And Resource C- trol (IC-PARC), speaking on \ECLiPSe: Declarative Specic ation and Scalable Implementation.