Links to Projects

• SQL Foundations
• XML Constraints
• Complex-value Databases
• Data Dependencies
• Conceptual Modelling

Constraints on SQL Data: Foundations for a Data-Intensive Society

This research is supported by the Marsden fund council from Government funding, administered by the Royal Society of New Zealand.

The project is joint work with Dr. Henning Koehler and Prof. Dr. Sven Hartmann from the Clausthal University of Technology, Germany. Many other colleagues also greatly contribute to this project.

We have received a Marsden grant for the period between March 2012 - February 2015 which totals NZD 405.000.

A detailed project description can be found here.

Some publications associated with this project are:

• The implication problem of data dependencies over SQL table definitions: axiomatic, algorithmic and logical characterizations (with S. Hartmann). ACM Transactions on Database Systems, Volume 37(2) , Article ?, to appear in June 2012. (pdf-file)
• Design by example for SQL table definitions with functional dependencies (with S. Hartmann and M. Kirchberg). The VLDB Journal, Volume 21(1) , pages 121-144, 2012. (pdf-file)
• Characterizations of multivalued dependency implication over undetermined universes. Journal of Computer and System Sciences , Volume 78(4), pages 1026-144, 2012. (pdf-file)
• Armstrong databases: validation, consolidation and communication of conceptual models with perfect test data Proceedings of the 8th Asia-Pacific Conference on Conceptual Modeling - APCCM 2012, Melbourne, Australia, January 30 - February 2, Conferences in Research and Practice in Information Technology, Volume 130, pages 3-20. (pdf-file)
• Armstrong Databases and Reasoning for Functional Dependencies and Cardinality Constraints over Partial Bags (with H. Koehler, S. Hartmann and B. Thalheim) Proceedings of the 7th International Symposium on Foundations of Information and Knowledge Systems - FoIKS 2012, Kiel, Germany, 5-9 March, Springer Lecture Notes in Computer Science, Volume 7153, pages 164-183. (pdf-file)
• Foundations for a Fourth normal form over SQL-like databases (with F. Ferrarotti, H. Koehler, S. Hartmann and M.W. Vincent) Conceptual Modelling and Its Theoretical Foundations - Essays Dedicated to Bernhard Thalheim on the Occasion of His 60th Birthday, Springer Lecture Notes in Computer Science, Volume 7260, pages 85-100. (pdf-file)
• Discovery of keys from SQL tables (with V. Le and M. Memari) Proceedings of the 17th International Conference on Database Systems for Advanced Applications - DASFAA 2012, Busan, Korea, 15-19 April, Springer Lecture Notes in Computer Science, Volume 7238, pages 48-62. (pdf-file)

Cardinality Constraints for XML - Challenging the Tradeoff between Expressiveness and Tractability

This research was supported by the Marsden fund council from Government funding, administered by the Royal Society of New Zealand.

The project is joint work with Prof. Dr. Sven Hartmann from the Clausthal University of Technology, Germany, and Dr. Flavio Ferrarotti from the School of Information Management, Victoria University of Wellington, New Zealand.

We have received a Marsden grant for the period between March 2009 - February 2012 which totals NZD 400.000.

A detailed project description can be found here.

Some publications associated with this project are:

• A precious class of cardinality constraints for flexible XML data processing (with F. Ferrarotti and S. Hartmann). Proceedings of the 30th International Conference on Conceptual Modeling - ER 2011, Brussels, Belgium, October 31 - November 3, Springer Lecture Notes in Computer Science, Volume 6998, pages 175-188. (pdf-file)
• Promoting the semantic capability of XML keys (with F. Ferrarotti, S. Hartmann and J. Wang). Proceedings of the Seventh International XML Symposium - XSym 2010, September 17, 2010, Singapore, Springer Lecture Notes in Computer Science, Volume 6309, pages 144-153. (pdf-file)
• Numerical constraints on XML data (with S. Hartmann). Information and Computation, Volume 208(5), pages 521-544, 2010. (pdf-file)
• Sample-based decision support for specifying XML constraints (with S. Hartmann and T. Trinh). Journal of Research and Practice in Information Technology, Volume 42(1), pages 15-36, 2010.
• Efficient reasoning about a robust XML key fragment (with S. Hartmann). ACM Transactions on Database Systems, Volume 34(2), Article 10, 33 pages, June 2009. (pdf-file)
• Expressive, yet Tractable XML Keys (with S. Hartmann).Proceedings of 12th International Conference on Extending Database Technology - EDBT 2009, March 24-26, 2009, Saint-Petersburg, Russia, ACM International Conference Proceeding Series, Volume 360, ISBN 978-1-60558-422-5.
• On the Notion of an XML key (with S. Hartmann, H. Koehler, T. Trinh, and J. Wang). In Proceedings of the Third International Workshop on Semantics in Data and Knowledge Systems - SDKB 2008, Lecture Notes in Computer Science Volume 4925, pages 114-123, Springer, ISBN: 9783540885931.
• Numerical keys for XML (with S. Hartmann), in the Proceedings of the Fourteenth International Workshop on Logic, Language, Information and Computation - WoLLIC 2007, Rio de Janeiro, Brazil, Lecture Notes in Computer Science Volume 4576, pp. 203-217, ISBN: 9783540734437
• Unlocking keys for XML trees (with S. Hartmann), in the Proceedings of the Eleventh International Conference on Database Theory - ICDT 2007, Barcelona, Spain, Lecture Notes in Computer Science Volume 4353, pp. 104-118, ISBN: 9783540692690
• Know your Limits: Enhanced XML Modeling with Cardinality Constraints (with T. Trinh), ER-Tutorial, In Proceedings of the tutorials, posters, panels and industrial contributions at the 26th International Conference on Conceptual Modeling - ER 2007, Conferences in Research and Practice in Information Technology, Volume 83, pp. 19-30, ISBN 978-1-920682-64-4
• XML Query Optimisation: Specify your Selectivity (with S. Hartmann), in the Proceedings of the 2nd International Workshop on XML Data Management Tools and Techniques - DEXA Workshops 2007, Regensburg, Germany, IEEE Computer Society, pp. 30-34, ISBN: 0-7695-2932-1.

Investigating Complex-value Database Design Problems using Brouwerian Algebras

This research was supported by the Marsden fund council from Government funding, administered by the Royal Society of New Zealand.

The project was a continuation of my PhD, and was supported by a Marsden Fast-Start grant in 2006 and 2007.

The final report can be downloaded as pdf document here.

The project involves joint work with Prof. Dr. Sven Hartmann from the Clausthal University of Technology, Germany, Prof. Dr. Klaus-Dieter Schewe from the Information Science Research Centre, New Zealand, and Dr. Henning Koehler.

Some publications associated with this project are:

• Armstrong axioms and Boyce-Codd-Heath Normal Form under bag semantics (with H. Koehler). Information Processing Letters, Volume 110(16), pages 717-724, 2010. (pdf-file)
• Characterising nested database dependencies by fragments of propositional logic (with S. Hartmann). Annals of Pure and Applied Logic, Volume 152(1-3), pages 84-16.
• On weak functional dependencies - full propositional expressiveness for the database practitioner (with S. Hartmann). Journal of Universal Computer Science, Volume 115(1), pages 112-156. (pdf-file)
• Lossless Decompositions in Complex-valued Databases (with H. Koehler). In the Proceedings of the 5th International Symposium on Foundations of Information and Knowledge Systems - FoIKS 2008, Pisa, Italy, Lecture Notes in Computer Science Volume 4932, pages 329-347, Springer, ISBN: 9783540776833.
• Deciding Implication for Functional Dependencies in Complex-value databases (with S. Hartmann), Theoretical Computer Science, Volume 364(2), pp. 212-240
• Axiomatising Functional Dependencies in the Presence of Records, Lists, Sets and Multisets (with S. Hartmann, K.-D. Schewe), Theoretical Computer Science, Volume 355(2), pp. 167-196
• Functional and Multivalued Dependencies in Nested Databases generated by Record and List Constructor (with S. Hartmann, K.-D. Schewe), Annals of Mathematics and Artificial Intelligence, Volume 46(1-2), pp. 114-164
• The Nested List Normal Form for Functional and Multivalued Dependencies (with S. Hartmann), in the Proceedings of the Fourth International Symposium on Foundations of Information and Knowledge Systems - FoIKS 2006, Budapest, Hungary, Lecture Notes in Computer Science Volume 3861, pp. 135-156, ISBN: 3540317821

Adequate Reasoning about Data Dependencies in Relational Databases

This research project is based on Joachim Biskup's alternative notion of implication for data dependencies, in which the underlying set of attributes is not fixed. One of the aims of this project is the clarification of the complementation rule for multivalued dependencies (MVDs) as a mere means of database normalization. We have extended Biskup's findings into different directions:

1. identify all axiomatizations of MVDs that clarify the role of the complementation rule in fixed universes
2. identify all axiomatizations of MVDs in undetermined universes
3. extend these findings to database relations that permit null values
4. extend these findings to full hierarchical dependencies
5. extend these findings to weak multivalued dependencies
6. extend these findings to full first-order hierarchical decompositions and the permutation rule
7. extend these findings to include functional dependencies as well (in an adequate axiomatisation no inference of a functional dependency should require the application of the complementation rule)

The project involves joint work with Prof. Dr. Joachim Biskup from the University of Dortmund, Germany, Prof. Dr. Sven Hartmann from the Clausthal University of Technology, and Dr. Flavio Ferrarotti from the School of Information Management, Victoria University of Wellington, New Zealand.

Some publications associated with this project are:

• Appropriate inferences of data dependencies in relational databases (with J. Biskup). Annals of Mathematics and Artificial Intelligence, Volume 63(3-4) , 213-255, 2011. (pdf-file)
• On the Role of the Complementation Rule for Data Dependencies over Incomplete Relations (with F. Ferrarotti and S. Hartmann). Proceedings of the 17th International Workshop on Logic, Language, Information and Computation - WoLLIC 2010, Brasilia, Brazil, 2010, Springer Lecture Notes in Artificial Intelligence LNCS/LNAI, Volume 6188, pages 136-147. (pdf-file)
• On inferences of weak multivalued dependencies (with S. Hartmann). Fundamenta Informaticae, Volume 92(1-2), pages 83-102. (pdf-file)
• Spoilt for Choice: Full First-Order Hierarchical Decompositions. Proceedings of 16th International Workshop on Logic, Language, Information and Computation - WoLLIC 2009, June 21-24, 2009, Tokyo, Japan, Springer Lecture Notes in Computer Science, FoLLI/LNAI, Volume: 5514, pages 256-267.
• Appropriate Reasoning about Data Dependencies in Fixed and Undetermined Universes (with J. Biskup), In the Proceedings of the 5th International Symposium on Foundations of Information and Knowledge Systems - FoIKS 2008, Pisa, Italy, Lecture Notes in Computer Science Volume 4932, pages 57-76, Springer, ISBN: 9783540776833.
• Charting the Completeness Frontier of Inference Systems for Multivalued Dependencies. Acta Informatica, Volume 45(7-8), pages 565-591.
• On the implication of multivalued dependencies in partial database relations. International Journal of Foundations of Computer Science, Volume 19(3), pages 691-715.
• Full Hierarchical Dependencies in fixed and undetermined universes (with S. Hartmann, H. Koehler), Annals of Mathematics and Artificial Intelligence, Volume 50(1-2), pages 195-226.
• On a Problem of Fagin concerning Multivalued Dependencies in Relational Databases (with S. Hartmann), Theoretical Computer Science, Volume 353(1-3), pp. 53-62

Foundations and Applications of Conceptual Modelling and Requirements Acquisition

In this project we look at various aspects of data modelling and requirements acquisition, including:

1. Collection types in ER diagrams and their mapping to logical data models
2. Guidelines for the transformation of natural language requirements into an ER schema
3. Automated decision support for the acquisition of meaningful integrity constraints
4. The role of sample and perfect sample databases for requirements acquisition
5. Propagation of cardinality constraints to other data models

The project involves joint work with Dr. Pavle Mogin from the Victoria University of Wellington, New Zealand, Prof. Dr. Sven Hartmann from the Clausthal University of Technology, Germany, Dr. Markus Kirchberg from the Agency for Science, Technology and Research (A*STAR), Singapore, Prof. Dr. Klaus-Dieter Schewe from the Information Science Research Centre, New Zealand, and Prof. Dr. Bernhard Thalheim from the University of Kiel, Germany.

Some publications associated with this project are:

• Formal concept discovery in Semantic Web data (with M. Kirchberg, E. Leonardi, Y.S. Tan, R.K.L. Ko, and B.S. Lee) Proceedings of the 10th International Conference on Formal Concept Analysis - ICFCA 2012, Leuven, Belgium, 6-10 May, Springer Lecture Notes in Computer Science, Volume , pages 164-179. (pdf-file)
• Empirical evidence of the usefulness of Armstrong relations in the acquisition of meaningful functional dependencies (with W.-D. Langeveldt). Information Systems, Volume 35(3), pages 352-374, 2010. (pdf-file)
• Constraint acquisition for Entity-Relationship models (with S. Hartmann and T. Trinh). Data and Knowledge Engineering Volume 68(10), pages 1128-1155, 2009. (pdf-file)
• Constraint Acquisition - You can Chase but you cannot find (with S. Hartmann and T. Trinh), in the Proceedings of the 5th Asia-Pacific Conference on Conceptual Modeling - APCCM 2008, Wollongong, Australia, Conferences in Research and Practice in Information Technology, Vol. 79, pages 59-68, ISBN: 9781920682606.
• Collection Types in Entity-Relationship Modeling (with S. Hartmann), in the Proceedings of the Twenty-Sixth International Conference on Conceptual Modeling - ER 2007, Auckland, New Zealand, Lecture Notes in Computer Science Volume 4801, pp. 307-322, ISBN: 9783540755623.
• English Sentence Structures and EER Modeling (with S. Hartmann), in the Proceedings of the Fourth Asia-Pacific Conference on Conceptual Modeling - APCCM 2007, Ballarat, Australia, Conferences in Research and Practice in Information Technology, Volume 67, pp. 27-35, 2007, ISBN: 1-920-68235-X
• Error-Robust Functional Dependencies (with S. Hartmann, K.-D. Schewe, B. Thalheim), Fundamenta Informaticae, Volume 59(4), pages 365-372, 2004.
• A New Normal Form for Conceptual Databases (with S. Hartmann, K.-D. Schewe), Proceedings of the 13th European-Japanese Conference on Information Modelling and Knowledge Bases - EJC 2003, Kitakyushu, Japan, IOS Press 2004, Frontiers in Artificial Intelligence and Applications, Vol. 105, pages 88-105, ISBN: 1-58603-396-4.
• Axiomatizing functional dependencies in the Higher-Order Entity-Relationship Model (with S. Hartmann, A. Hoffman, K.-D. Schewe), Inf. Process. Lett. Vol. 87(3), pages 133-137, 2003.
• On the Implication Problem for Functional Dependencies in the Higher-Order Entity-Relationship Model (with M. Kirchberg), Proceedings of the 14th Australasian Database Conference - ADC 2003, Adelaide, South Australia,Vol. 17, pages 115-124, ISBN: 0-909-92595-X.