MOSS'09 is a Spring School hosted by the Knowledge Systems Group at Meraka. It is aimed at researchers and research students based in South Africa who are interested in data management using formal ontologies.

Organizers: Aurona Gerber, Arina Britz, Gavin Rens

Credits: Registered Honours and Masters students can earn credits upon successful completion of a project, which will form part of the course. If you want to attend the course for credits, please contact your university to obtain permission and make formal arrangements with us.

Lectures: MOSS'09 will be offered over 12 days, starting 7 September. Lectures start at 9:00. Practical sessions will generally be offered during the afternoon, and will end by 17:00 each day at the latest.

Prerequisites: Please note that this course is a post-graduate course in computational logic, including mathematical database foundations and description logic. In order to really get benefit from the lectures, a basic knowledge of logic and mathematical concepts is essential.

7-8 September: Basics (Mathematical foundations; Introduction to computational complexity; Introduction to propositional and first-order logic). Presenters: Thomas Fogwill and Ronell Alberts from Meraka. Course web site: http://ksg.meraka.csir.co.za/~tfogwill/teaching/moss09/intro_logic/

9-10 September: Introduction to description logics. Presenter: Anni-Yasmin Turhan from TU Dresden.

Description Logics are a successful family of logic-based knowledge representation formalisms, which can be used to represent the conceptual knowledge of an application domain in a structured and
formally well-understood way. Based on their formal semantics, many reasoning procedures have been defined and algorithms to compute them have been investigated for a range of Description Logics. Ontology languages such as OWL in the Semantic Web have greatly increased interest in Description Logics and related techniques in recent years,
since they are based on expressive Description Logics.

This course begins with an introduction of the basic principles underlying knowledge representation with Description Logics. Then we turn to reasoning procedures and practical applications of Description
Logic systems.

The slides are available for download here.

11 September: Mathematical foundations of databases. Presenters: Thomas Fogwill and Ronell Alberts from Meraka.

14 September: Unisa post-graduate symposium. Research students registered at Unisa will have the opportunity to present their work at the symposium, which is hosted by Unisa. This day is not officially part of MOSS'09.

15-16 September: Mathematical foundations of databases (continued). Presenters: Thomas Fogwill and Ronell Alberts from Meraka.

17-23 September: Ontology-based data management. Presenters: Lecturer: Diego Calvanese. Exercises and labs: Mariano Rodriguez-Muro.

Course duration: 20 hours of lectures, 10 hours of labs.

Objectives and description of the course: Both ontology-based systems and database management systems are used to maintain information about a domain of interest and provide mechanisms to access and manipulate such information.  However the assumptions that traditionally are at the basis of these two kinds of systems are fundamentally different.  On the one hand, in ontology-based systems, data is assumed to be incomplete, i.e., the open-world assumption is made, and an ontology is stored in addition to the extensional information. The ontology maintains complex relationships at the intensional level and is used at query time to infer new knowledge.  On the other hand, DB systems work under the closed-world assumption and do not exploit intensional information at query time, which makes them capable of managing efficiently very large amounts of data.  Recently, various application domains, ranging from biological to enterprise data management, require to combine the assumptions underlying both types of systems, namely the management of very large amounts of data, as in DBs, under the open-world assumption and in the presence of complex constraints in an ontology.  Several novel challenges arise in this context and need to be addressed, such as: (i) the trade-off between the expressive power of the ontology language and the efficiency of computing answers to queries; (ii) the impedance mismatch between the abstract objects in the ontology and the values appearing in data sources; (iii) the processing of queries posed over the ontology by accessing the data stored in relational sources; (iv) the integration of multiple data sources.  In this course, we will analyze these issues in depth and will propose solutions based on recent research results for tractable Description Logics and in Ontology-Based Data Access.  The theoretical lectures will be complemented by lab sessions in which participants will familiarize with a state-of-the art ontology-based data access system, and implement a project in such a system.

Outline of the lectures (20 hours):

1.  Introduction to ontology-based data management
1.    Introduction to ontologies
2.    Ontology languages
2. Description Logics and the DL-Lite family
1.    An introduction to DLs
2.    DLs as a formal language to specify ontologies
3.    Queries in Description Logics
4.    The DL-Lite family of tractable DLs
3. Linking ontologies to relational data
1.    The impedance mismatch problem
2.    OBDA systems
3.    Query answering in OBDA systems
4. Reasoning in the DL-Lite family
1.    TBox reasoning
2.    TBox & ABox reasoning
3.    Complexity of reasoning in Description Logics
4.    Reasoning in the Description Logic DL-Lite

Article:
A quite extensive article that contains essentially all the material that will be presented during 17-23 can be found here.

Slides:
The slides used in this course are available here in three versions: 1 slide per page, 2 slides per page, and 4 slides per page  (convenient for printing).

CVs:
Diego Calvanese (http://www.inf.unibz.it/~calvanese/) is associate professor at the KRDB Research Centre of the Faculty of Computer Science, Free University of Bozen-Bolzano, where he teaches courses on theory of computing, formal languages, knowledge bases and databases, and information integration.  His research interests include formalisms for knowledge representation and reasoning, ontology languages, Description Logics, conceptual data modeling, data integration, semistructured data management, and web service modeling and composition.  He participated in several national and international research projects, and he has been the coordinator of the EU STREP FET Project "Thinking ONtologiES" (TONES).  He has been co-chair of the Int. Workshops on Description Logics DL 2003 and DL 2007, and PC co-chair of the Int. Conference on Web Reasoning and Rule Systems RR 2008.  He is the author of more than 150 publications in international journals, conferences, and workshops, and he is one of the editors of the "Description Logics Handbook".

Mariano Rodriguez-Muro is research associate at the KRDB Research Centre of the Faculty of Computer Science, Free University of Bozen-Bolzano, where he is currently completing his PhD on the optimization and practical usability of systems for accessing data through ontologies.  He is contributing to the development of the state-of-the-art QuOnto ontology-based data access system.

Practicals: Please bring your own computer for the practical sessions.

Venue: Meraka Auditorium.  Directions can be found on the Meraka website. Or see the location on a Google map.

Prerequisites: You need a basic background in Description Logics and Databases if you plan to attend the sessions on 17-23 September. If you do not have this background, please attend the preparatory sessions on 7-16 September.

Cost: Attendance is free, but please register by sending an email to moss.ksg@gmail.com. We only have seating for 40 attendants.  We have a cafeteria on site for lunch or other refreshments. Please make your own travel and accommodation arrangements.