Project Outline and Aims
As the use of XML on the Web has become more widespread, there is an associated need to transform XML in various ways to meet differing requirements. Most such transformations are performed using either XSLT or XQuery, both of which use XPath for the selection of elements.
Where transformations or queries are complicated or are to be performed on large documents, there is a need to optimise XPath expressions in order to rewrite them into more efficient forms. This project investigates
- the satisfiability of XPath expressions,
- the equivalence (and containment) of XPath expressions,
- the identification of redundant parts of XPath expressions, and
- the extent to which XPath expressions can be minimised efficiently.
Collectively, our papers on minimising XPath expressions and containment of XPath expressions have received over 200 citations according to Google scholar.
Funding and Staffing Details
The project is being undertaken by Peter Wood and Manizheh Montazerian, who is working in the area for her PhD.
Project publications
- M. Montazerian and P.T. Wood, ``Chasing One's Tail: XPath Containment Under Cyclic DTDs,'' in Proc. 13th International Symposium on Database Programming Languages (August 29, Seattle, Washington), 2011.
- M. Montazerian, P.T. Wood and S.R. Mousavi, ``XPath Query Satisfiability is in PTIME for Real-World DTDs,'' in Proc. Fifth Int. XML Database Symposium, (Vienna, Austria, Sept. 23-24), LNCS 4704, Springer-Verlag, 2007, pp. 17-30.
- P.T. Wood, ``Containment for XPath Fragments under DTD Constraints,'' in Proc. 9th Int. Conf. on Database Theory (Siena, Italy, Jan. 8-10), LNCS 2572, Springer-Verlag, 2003, pp. 300-314.
- P.T. Wood, ``Minimising Simple XPath Expressions,'' in Proc. 4th Int. Workshop on the Web and Databases (WebDB) (Santa Barbara, California, May 24-25), 2001, pp. 13-18.
- P.T. Wood, ``On the Equivalence of XML Patterns,'' in Proc. 1st Int. Conf. on Computational Logic (Imperial College, UK, July 24-28), LNAI 1861, Springer-Verlag, 2000, pp. 1152-1166.
- P.T. Wood, ``Rewriting XQL Queries on XML Repositories,'' in Proc. 17th British National Conf. on Databases (Univ. of Exeter, UK, July 3-5), LNCS 1832, Springer-Verlag, 2000, pp. 209-226.
- P.T. Wood, ``Optimising Web Queries Using Document Type Definitions,'' in 2nd ACM Workshop on Web Information and Data Management (WIDM'99) (Kansas City, Missouri, USA, Nov. 5-6), 1999, pp. 28-32.