Datalog+- Multidimensional Contexts for Data Quality: Quality Data
Extraction and Query Answering Algorithms Assessment
Leopoldo Bertossi
Carleton Unviversity, Ottawa, Canada
Andrea Calì
University of London, Birkbeck College, London, UK
DEIB - PT1 Room
December 1st, 2016
2.30 pm
Contact:
Letizia Tanca
Research Line:
Data, web, and society
Carleton Unviversity, Ottawa, Canada
Andrea Calì
University of London, Birkbeck College, London, UK
DEIB - PT1 Room
December 1st, 2016
2.30 pm
Contact:
Letizia Tanca
Research Line:
Data, web, and society
Abstract
Data quality and data cleaning are context dependent activities. In previous work a context model for the assessment of the quality of the data in a database instance was proposed. In the first part of this presentation (given by L. Bertossi) we show how
to specify contexts with dimensions, making it possible a multidimensional data quality assessment. A database instance under quality assessment is mapped into the context for additional analysis and processing, enabling quality assessment. Contexts are represented as ontologies written in Datalog+-, which is used for representing dimensional constraints, and dimensional rules, and also for doing query answering based on dimensional navigation, which becomes an important auxiliary activity in the assessment of data. We show that the Datalog+- ontologies fall in the Weakly-Sticky (WS) class.
It the second part of this talk (given by A. Cali) we start from the fact that for the WS class conjunctive query answering is tractable. However, until very recently there were no practical algorithms available. We present new rewriting-based algorithms for conjunctive query answering.
This is join work with Mostafa Milani (Carleton University).
to specify contexts with dimensions, making it possible a multidimensional data quality assessment. A database instance under quality assessment is mapped into the context for additional analysis and processing, enabling quality assessment. Contexts are represented as ontologies written in Datalog+-, which is used for representing dimensional constraints, and dimensional rules, and also for doing query answering based on dimensional navigation, which becomes an important auxiliary activity in the assessment of data. We show that the Datalog+- ontologies fall in the Weakly-Sticky (WS) class.
It the second part of this talk (given by A. Cali) we start from the fact that for the WS class conjunctive query answering is tractable. However, until very recently there were no practical algorithms available. We present new rewriting-based algorithms for conjunctive query answering.
This is join work with Mostafa Milani (Carleton University).
Short Bio
Leopoldo Bertossi has been Full Professor at the School of Computer Science, Carleton University (Ottawa, Canada) since 2001.
He is also a Faculty Fellow of the IBM Center for Advanced Studies (IBM Toronto Lab).
He has been the theme leader for "Data Quality and Data Cleaning" of the "NSERC Strategic Network for Data Management for Business Intelligence" (BIN), a project that since 2009 has involved more than fifteen academic researchers across Canada plus several industrial partners.
Until 2001 he was professor and departmental chair (1993-1995) at the Department of Computer Science, PUC; and also the President of the Chilean Computer Science Society (SCCC) in 1996 and 1999-2000.
He has been visiting professor at the computer science departments of the universities of Toronto (1989/90), Wisconsin-Milwaukee (1990/91), Marseille-Luminy (1997) and visiting researcher at the Technical University Berlin (1997/98), visiting researcher and professor at the Free University of Bolzano-Bozen (Italy). In 2006 he was a visiting researcher at the Technical University of Vienna as a Pauli Fellow of the "Wolfgang Pauli Institute (WPI) Vienna".
Prof. Bertossi's research interests include database theory, business intelligence, data quality, data integration, peer data management, semantic web, intelligent information systems, knowledge representation, logic programming, and computational logic.
He obtained a PhD in Mathematics from the Pontifical Catholic University of Chile (PUC) in 1988. He did a PhD thesis on mathematical logic (model theory) under the supervision of Prof. Joerg Flum (University of Freiburg, Germany).
Andrea Calì is a Senior Lecturer at the Department of Computer Science and Information Systems of the University of London, Birkbeck College. He holds a MEng in Electronic Engineering and a PhD in Computer Engineering, both from the University of Rome "La Sapienza". His research interests include Database Theory, Deep Web, Semantic Web and Ontology Reasoning, Information Integration and Linked Data querying. Among other interests, he investigates the computational complexity of fundamental problems in data processing under knowledge bases. His is currently researching how to automatically integrate Web data in decision support and matchmaking systems.
He is also a Faculty Fellow of the IBM Center for Advanced Studies (IBM Toronto Lab).
He has been the theme leader for "Data Quality and Data Cleaning" of the "NSERC Strategic Network for Data Management for Business Intelligence" (BIN), a project that since 2009 has involved more than fifteen academic researchers across Canada plus several industrial partners.
Until 2001 he was professor and departmental chair (1993-1995) at the Department of Computer Science, PUC; and also the President of the Chilean Computer Science Society (SCCC) in 1996 and 1999-2000.
He has been visiting professor at the computer science departments of the universities of Toronto (1989/90), Wisconsin-Milwaukee (1990/91), Marseille-Luminy (1997) and visiting researcher at the Technical University Berlin (1997/98), visiting researcher and professor at the Free University of Bolzano-Bozen (Italy). In 2006 he was a visiting researcher at the Technical University of Vienna as a Pauli Fellow of the "Wolfgang Pauli Institute (WPI) Vienna".
Prof. Bertossi's research interests include database theory, business intelligence, data quality, data integration, peer data management, semantic web, intelligent information systems, knowledge representation, logic programming, and computational logic.
He obtained a PhD in Mathematics from the Pontifical Catholic University of Chile (PUC) in 1988. He did a PhD thesis on mathematical logic (model theory) under the supervision of Prof. Joerg Flum (University of Freiburg, Germany).
Andrea Calì is a Senior Lecturer at the Department of Computer Science and Information Systems of the University of London, Birkbeck College. He holds a MEng in Electronic Engineering and a PhD in Computer Engineering, both from the University of Rome "La Sapienza". His research interests include Database Theory, Deep Web, Semantic Web and Ontology Reasoning, Information Integration and Linked Data querying. Among other interests, he investigates the computational complexity of fundamental problems in data processing under knowledge bases. His is currently researching how to automatically integrate Web data in decision support and matchmaking systems.
