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Reasoning about Keys for XML

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1037-1063
Number of pages27
JournalInformation Systems
Issue number8
Publication statusPublished - 2003


We study absolute and relative keys for XML, and investigate their associated decision problems. We argue that these keys are important to many forms of hierarchically structured data including XML documents. In contrast to other proposals of keys for XML, we show that these keys are always (finitely) satisfiable, and their (finite) implication problem is finitely axiomatizable. Furthermore, we provide a polynomial time algorithm for determining (finite) implication in the size of keys. Our results also demonstrate, among other things, that the analysis of XML keys is far more intricate than its relational counterpart.

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