Minimising simple XPath expressions

Wood, Peter (2001) Minimising simple XPath expressions. In: Mecca, G. and Simeon, J. (eds.) WebDB 2001: Proceedings of the Fourth International Workshop on the Web and Databases. WebDB, pp. 13-18.

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Abstract

We consider a subset of XPath expressions, called simple XPath expressions, which correspond to a class of conjunctive queries. We show that, in the absence of a DTD, each simple XPath expression has a unique minimal equivalent expression which can be found in polynomial time. We then consider D-equivalence, the equivalence of expressions with respect to the set of documents valid for a given DTD D. We show that a simple XPath expression P does not necessarily have a unique minimal D-equivalent expression. However, if P is reduced (there are no wildcards in it), then there is a unique minimal equivalent expression, but we show that deciding whether two reduced expressions are D-equivalent is coNP-hard.

Metadata

Item Type:	Book Section
School:	Birkbeck Faculties and Schools > Faculty of Science > School of Computing and Mathematical Sciences
Depositing User:	Sarah Hall
Date Deposited:	18 Oct 2021 14:49
Last Modified:	09 Aug 2023 12:52
URI:	https://eprints.bbk.ac.uk/id/eprint/46326

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