Using methods of declarative logic programming for intelligent information agents

Abstract

At present, the search for specific information on the World Wide Web is faced with several problems, which arise on the one hand from the vast number of information sources available, and on the other hand from their intrinsic heterogeneity, since standards are missing. A promising approach for solving the complex problems emerging in this context is the use of multi-agent systems of information agents, which cooperatively solve advanced information-retrieval problems. This requires advanced capabilities to address complex tasks, such as search and assessment of information sources, query planning, information merging and fusion, dealing with incomplete information, and handling of inconsistency.In this paper, our interest lies in the role which some methods from the field of declarative logic programming can play in the realization of reasoning capabilities for information agents. In particular, we are interested to see in how they can be used, extended, and further developed for the specific needs of this application domain. We review some existing systems and current projects, which typically address information-integration problems. We then focus on declarative knowledge-representation methods, and review and evaluate approaches and methods from logic programming and nonmonotonic reasoning for information agents. We discuss advantages and drawbacks, and point out the possible extensions and open issues.

Combining Equilibrium Logic and Dynamic Logic

“…New applications in AI force us to extend the original language of ASP by some new concepts capable of supporting, for example, the representations of modalities, actions, ontologies or updates. Based on a tradition that was started by Alchourrón, Gärdenfors and Makinson and also by Katsuno and Mendelzon [1,13], several researchers have proposed to extend ASP by operations allowing to update or revise a given ASP program through a new piece of information [3,17,15,16]. The resulting formalisms are quite complex, and we think it is fair to say that it is difficult to grasp what the intuitions should be like under these approaches.…”

A knowledge-based approach for selecting information sources

“…Mediators (Wiederhold 1993) and special information agents ("middle agents" (Decker et al 1997)), which provide various services including finding, selecting, and querying relevant information sources, play an important role here. The potential of knowledge-based approachesand in particular of logic programming-for developing reasoning components for intelligent information agents is recognized in the AI community and outlined, e.g., by Dimopoulos and Kakas (2001), Eiter et al (2002b), and Sadri and Toni (2000).…”

Revising Knowledge in Multi-agent Systems Using Revision Programming with Preferences

“…The problem is compounded by the fact that incoming knowledge could be contradictory-either conflicting with the local knowledge or with other incoming items-incomplete, or unreliable. Recently a number of formalisms have been proposed [16,4,2,20,8] to support dynamic updates of (propositional) logic programming theories; they provide convenient frameworks for describing knowledge base updates as well as constraints to ensure user-defined principles of consistency. These types of formalisms have been proved effective in the context of MAS (e.g., [12]).…”