Diego Calvanese (Free University of Bozen-Bolzano, Italy)
Query Answering over Description Logic Ontologies
Abstract: Description Logics (DLs) provide the formal foundation for ontology languages, and they have been advocated as formalisms for modeling the domain of interest in various settings, including the Semantic Web, data and information integration, and ontology-based data access. An important requirement there is the ability to answer complex database-like queries, while taking into account both extensional and intensional domain knowledge. The task of answering conjunctive queries and unions thereof has been investigated intensively in the last years for a variety of DLs, and considering both data complexity, i.e., the complexity measured in the size of the extensional information only, and combined complexity. On the one hand, it has been shown to be in general (exponentially) more difficult than the standard reasoning tasks of concept satisfiability and subsumption; on the other hand a broad range of techniques have been developed. In this talk we overview the main results and techniques developed in the last years for answering (unions of) conjunctive queries over DL ontologies, ranging from tableaux algorithms and techniques based on automata on infinite trees for expressive DLs, to rewriting based approaches for lightweight DLs. These results, accompanied by matching lower bounds, have contributed to shaping the computational complexity picture for ontology-based query answering.
Short Bio: Diego Calvanese is a professor at the KRDB Research Centre for Knowledge and Data, Free University of Bozen-Bolzano, Italy. His research interests include formalisms for knowledge representation and reasoning, ontology languages, description logics, conceptual data modeling, data integration, graph data management, data-aware process verification, and service modeling and synthesis. He is actively involved in several national and international research projects in the above areas. He is the author of more than 250 refereed publications, including ones in the most prestigious international journals and conferences in Databases and Artificial Intelligence, and he is one of the editors of the Description Logic Handbook. In 2012-2013 he has been a visiting researcher at the Technical University of Vienna as Pauli Fellow of the "Wolfgang Pauli Institute". He will be the program chair of PODS 2015.
Agata Ciabattoni (Vienna University of Technology, Austria)
Tools for the investigation of substructural and paraconsistent logics
Abstract: We describe our tools for introducing sequent-style calculi for large classes of logics and using them to prove various results about these logics in a uniform and automated way. For the case studies of substructural and of paraconsistent logics the introduced calculi are used to prove standard completeness, decidability, and to provide new semantic foundations using non-deterministic matrices.
Short Bio: Agata Ciabattoni is a professor for nonclassical logics in computer science at the Faculty of Informatics of the Vienna University of Technology. In 2011 she has been awarded a START prize (the Austrian equivalent of the ERC starting grant) for her project Non classical proofs: Theory, Applications and Tools. She is working on theoretical aspects of nonclassical logics (proof theory and semantics), tools for their investigation, and applications (currently, medical expert systems and indology).
Hector Geffner (Universitat Pompeu Fabra in Barcelona, Spain)
How to solve a non-classical planning problem with a classical planner: the power of transformations
Abstract: Planning is the model-based approach to autonomous behavior, where a predictive models of the actions and sensors is used to generate the behavior for achieving goals. The main challenges in planning are computational as all models, whether featuring uncertainty and feedback or not, are intractable in the worst case when represented in compact form. Classical planning refers to the simplest form of planning where termination goals are to be achieved by applying deterministic actions to a fully known initial situation. In this talk, I'll review the inferences performed by classical planners that enable them for dealing with such problems, as well as the transformations that have been developed for using these same planners on more complex problems, by compiling a number of non-classical features away: features such as soft and temporally extended LTL goals, incomplete information and sensing, and multiple agents with nested beliefs. I'll also review some of the challenges.
Short Bio: Hector Geffner is an ICREA Research Professor at the Universitat Pompeu Fabra in Barcelona. He has a PhD in Computer Science from UCLA. He received the 1990 ACM Dissertation Award, and the 2009, 2010, and 2014 ICAPS Influential Paper Awards. He is a fellow of AAAI and ECCAI, Associate Editor of AIJ, and former Associate Editor of JAIR. He is also the author of the book "Default Reasoning", MIT Press, 1992, co-editor with Rina Dechter and Joseph Halpern of the book "Heuristics, Probability and Causality: A Tribute to Judea Pearl", College Publications, 2010, and co-author with Blai Bonet of "A Concise Introduction to Models and Methods for Automated Planning", Morgan & laypool Publishers, 2013.
Andreas Herzig (Université Paul Sabatier, France)
A simple logic for reasoning about actions, update, revision, argumentation, planning, and all that
Abstract: Dynamic logic is a powerful tool to reason about programs. In this talk we go beyond this application and present a simple variant of dynamic logic where atomic programs are assignments of propositional variables to true or false: Dynamic Logic of Propositional Assignments, abbreviated DL-PA. We show that many popular knowledge representation formalisms can be captured in DL-PA: update operations such as Winslett's `Possible Models Approach' and revision operations such as Dalal's, Dung argumentation frameworks and their modification, and planning tasks and their modification.
Short Bio: Andreas Herzig is a senior researcher at the French National Center for Scientific Research (CNRS) and works at the the Toulouse Computer Science Research Institute (IRIT). He studied computer science in Darmstadt and Toulouse and obtained a Ph.D. (1989) and a habilitation (1999) in Computer Science, both from Paul Sabatier University in Toulouse. He works at CNRS since 1990. Andreas's main research topic is the investigation of logical models of interaction, with a focus on logics for reasoning about knowledge, belief, time, action, intention and obligation, and the development of theorem proving methods for them. He currently investigates the integration of logics of belief and group belief with theories of action, in particular in the framework of dynamic epistemic logics.
Anthony Hunter (University College London, United Kingdom)
Towards Argument-based Persuasion Technologies
Abstract: In persuasion technologies, a system enters into a dialogue with a user to persuade them to undertake some action. An action might be a mental action such as believing something, or deciding something, or it might be a physical action such as buying something, voting for somebody, eating something, or taking some medicine, or it might be to not do some action such as not buying something, or not eating something, etc. Since a persuasion dialogue normally involves the exchange of arguments, computational models of argument are being developed for modelling persuasion dialogues. In this talk, we will review some of these developments, in particular for handling uncertainty that is inherent in persuasion dialogues, and consider what they offer for argument-based persuasion technologies.
Short Bio: Anthony Hunter is a Professor of Artificial Intelligence, and Head of the Intelligent Systems Group, in the Department of Computer Science at University College London (UCL). His research interests lie in the area of knowledge representation and reasoning, with particular emphasis on problems and opportunities arising from dealing with incomplete and inconsistent information. Currently, he is interested in computational models of argument, methods for aggregating knowledge from multiple sources, and measures of inconsistency in information.