It has been argued in the literature that current commercial query languages (SQL) do not have enough power and flexibility to express, in a easy and convenient way, many queries that database systems are being asked to solve nowadays. Complex new applications like Decision Support, Data Mining and E-commerce ask the database to solve queries involving complex relationships among sets of data items in the database.
In this project, we define a Query Language with Generalized Quantifiers (QLGQ), show how it can state complex questions in a simpler form than SQL, and study its implementation and optimization. The ultimate goal is to gain understanding of the trade-offs between language design and optimization. We expect that the study of QLGQ optimization will yield lessons that will help improve optimization in SQL, and suggest improvements to the language design.

• QLGQ is a logic-based language, so our first task is to make sure that it deals with all the annoyances of SQL, like nulls, duplicates and aggregates. We are currently developing a front-end (parser/checker/interpreter) for QLGQ so that it becomes a real language instead of just a pencil-and-paper language. A preliminary interface is available. Feel free to explore and use! If you do, please provide us with feedback (email)
• We are working on using the language in Information Extraction and Question Answering. documents with XML, using an extension of XQuery. Details will be available soon.
• We are using QLGQ to provide support for quantified queries in distributed environments. Current distributed systems (either mediated or peer-to-peer) only support Select-Project-Join queries and cannot handle quantified queries. Look for a paper coming soon!

• Bin Cao, A. Badia SQL Query Optimization Through Nested Relational Algebra, to appear in the ACM Transactions on Database Systems (will post as soon as final version is ready!).
• A. Badia, Stijn Vansummeren Non-Linear Prefixes in Query Languages, to appear in the Proceedings of the Principles of Database Systems (PODS) Conference, 2007 (will post as soon as final version is ready!).
• Bin Cao, A. Badia Optimization of Redundancy in SQL Queries , under review.
• A. Badia Question Answering and Database Querying: Bridging the Gap with Generalized Quantifiers, in Journal of Applied Logic, Special Issue on Questions and Answers: Theoretical and Applied Perspectives, Rafaella Bernardi and Bonnie Webber, eds., v.5, n. 1, March 2007, pages 3-19, Elsevier Publishers.
• Bin Cao, A. Badia Redundancy Awareness in SQL Queries, The Second International Special Workshop on Databases for Next-Generation Researchers (SWOD'06), held jointly with ICDE'06.
• Bin Cao Optimization of Complex Nested Queries in Relational Databases, Ph.D Workshop Papers, held jointly with ICDE'06.
• Bin Cao, A. Badia A Nested Relational Approach to Processing SQL Subqueries , in Proceedings of the ACM SIGMOD International Conference on Management of Data, pgs. 191-202, Baltimore, USA, June 2005.
• A. Badia Safety, Domain Independence and Generalized Quantification, Data and Knowledge Engineering, volume 38, number 2, pages 147-172, August 2001, Elsevier Publisher.
• A. Badia Extending Description Logics with Generalized Quantification, in Proceedings of the 11th International Symposium on Methodologies for Intelligent Systems (ISMIS'99), Lecture Notes in Artificial Intelligence, number 1609, pages 94-102, Ras and Skowron, editors, Springer-Verlag.
• Gyssens, M., Van Gucht, D. and Badia, A., Query Languages with Generalized Quantifiers, in Application of Logic Databases, Ramakrishnan, Ragu ed., Kluwer Academic Publishers, 1995. A first publication out of my thesis.

Please come back soon! Results and papers will be posted as research progresses

For those interested, some classical references on Generalized Quantifiers, including background material in logic and linguistics:

• Barwise, J. and R. Cooper, Generalized Quantifiers and Natural Language, Linguistic and Philosophy, volume 4, 1981.
• Dawar, A. and Hella, L., The Expressive Power of Finitely Many Generalized Quantifiers, in Proceedings of the 9th IEEE Symposium on Logic In Computer Science, 1994.
• Keenan, E. and Westerstahl, D., Generalized Quantifiers in Linguistics and Logic in Generalized Quantifiers in Natural Language, van Benthem, J. and ter Meulen, A., eds. Foris Publications, 1985.
• Kolaitis, P. and Vaannanen, J., Generalized Quantifiers and Pebble Games on Finite Structures, Proceedings of the 7th IEEE Symposium on Logic in Computer Science, 1992.
• Lindstrom, P., First Order Predicate Logic with Generalized Quantifiers, Theoria, volume 32, 1966. This is the classical reference for the concept, together with
• Mostowski, A., On a Generalization of Quantifiers, Fundamenta Mathematica, volume 44, 1957.
• Westerstahl, D., Quantifiers in Formal and Natural Languages, in Handbook of Philosophical Logic, volume IV, Gabbay, D. and Guenther, F., eds., Reidel Publishing Company, 1989.