Antonis Bikakis

DR-NEGOTIATE - A system for automated agent negotiation with defeasible logic-based strategies

This paper reports on a system for automated agent negotiation. It uses the JADE agent framework, and its major distinctive feature is the use of declarative negotiation strategies. The negotiation strategies are expressed in a declarative rules language, defeasible logic and are applied using the implemented defeasible reasoning system DR-DEVICE. The choice of defeasible logic is justified. The overall system architecture is described, and a particular negotiation case is presented in detail.

DR-BROKERING: A semantic brokering system

In this paper we study the brokering and matchmaking problem, that is, how a requesters requirements and preferences can be matched against a set of offerings collected by a broker. The proposed solution uses the Semantic Web standard of RDF to represent the offerings, and a deductive logical language for expressing the requirements and preferences. We motivate and explain the approach and architecture we propose, and report on a system implementing the described functionality in a multi-agent environment. Finally, we experimentally evaluate the core reasoning engine of the system.

A System for Nonmonotonic Rules on the Web

Defeasible reasoning is a rule-based approach for efficient reasoning with incomplete and inconsistent information. Such reasoning is, among others, useful for ontology integration, where conflicting information arises naturally; and for the modeling of business rules and policies, where rules with exceptions are often used. This paper describes these scenarios in more detail, and reports on the implementation of a system for defeasible reasoning on the Web. The system (a) is syntactically compatible with RuleML; (b) features strict and defeasible rules and priorities; (c) is based on a translation to logic programming with declarative semantics; and (d) is flexible and adaptable to different intuitions within defeasible reasoning.

DR-BROKERING - a defeasible logic-based system for semantic brokering

Electronic brokering is a good candidate for taking up semantic Web technology. In this paper we study the brokering and matchmaking problem that is, how a requesters requirements and preferences can be matched against a set of offerings collected by a broker. The proposed solution uses the semantic Web standard of RDF to represent the offerings, and a deductive logical language, based on non-monotonic reasoning, for expressing the requirements and preferences. We motivate and explain the approach we propose, and report on a prototypical implementation exhibiting the described functionality, in JADE agent environment.

FleXConf: A Flexible Conference Assistant Using Context-Aware Notification Services

Integrating context-aware notification services to ubiquitous computing systems aims at the provision of the right information to the right users, at the right time, in the right place, and on the right device, and constitutes a significant step towards the realization of the Ambient Intelligence vision. In this paper, we present FlexConf , a semantics-based system that supports location-based, personalized notification services for the assistance of conference attendees. Its special features include an ontology-based representation model, rule-based context-aware reasoning, and a novel positioning system for indoor environments.

The DR-Prolog Tool Suite for Defeasible Reasoning and Proof Explanation in the Semantic Web

In this work we present the design and general architecture of DR-Prolog, a system for defeasible reasoning and proof explanation in the Semantic Web, and the implementation of three different tools that constitute the DR-Prolog Tool Suite: (a) the DR-Prolog API; (b) the DR-Prolog Web application; and (c) the DR-Prolog desktop application. DR-Prolog supports reasoning with Defeasible Logic theories and ontological knowledge in RDF(S) and OWL, is compatible with RuleML, and enables extracting meaningful proof explanations for the answers it computes.

A context-aware meeting alert using semantic web and rule technology

This paper describes a context-aware meeting alert, which aims at alerting the user in time about upcoming scheduled calendar events, considering the state of the users context. This application integrates semantic web technology in RDF (for representing calendars), semantic web rules (for making a context dependent decision about the precise timing of the alert), and mobile technology for location sensing and message delivery. The outlined work is an experiment seeking to demonstrate the feasibility of applying efficient, semantically sound semantic web reasoning to mobile applications.

Visualization of Proofs in Defeasible Logic

The development of the Semantic Web proceeds in steps, building each layer on top of the other. Currently, the focus of research efforts is concentrated on logic and proofs, both of which are essential, since they will allow systems to infer new knowledge by applying principles on the existing data and explain their actions. Research is shifting towards the study of non-monotonic systems that are capable of handling conflicts among rules and reasoning with partial information. As for the proof layer of the Semantic Web, it can play a vital role in increasing the reliability of Semantic Web systems, since it will be possible to provide explanations and/or justifications of the derived answers. This paper reports on the implementation of a system for visualizing proof explanations on the Semantic Web. The proposed system applies defeasible logic, a member of the non-monotonic logics family, as the underlying inference system. The proof representation schema is based on a graph-based methodology for visualizing defeasible logic rule bases.

A deductive semantic brokering system

In this paper we study the brokering and matchmaking problem in the tourism domain, that is, how a requesters requirements and preferences can be matched against a set of offerings collected by a broker. The proposed solution uses the Semantic Web standard of RDF to represent the offerings, and a deductive logical language for expressing the requirements and preferences. We motivate and explain the approach we propose, and report on a prototypical implementation exhibiting the described functionality in a multi-agent environment.

A Multi-agent Environment for Serving Proof Explanations in the Semantic Web

In this work we present the design and implementation of a multi-agent environment for serving proof explanations in the Semantic Web. The system allows users or agents to issue queries, on a given RDF& rules knowledge base and automatically produces proof explanations for answers produced by a popular programming system (JENA), by interpreting the output from the proofs trace and converting it into a meaningful representation. It also supports an XML representation (a R2ML language extension) for agent communication, which is a common scenario in the Semantic Web. The system in essence implements a proof layer for rules on the Semantic Web empowering trust between agents and users.