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Journal of the ACM (JACM), Volume 51 Issue 1, January 2004

Foreword
Phokion Kolaitis, Victor Vianu
Pages: 1-1
DOI: 10.1145/962446.962447

Containment and equivalence for a fragment of XPath
Gerome Miklau, Dan Suciu
Pages: 2-45
DOI: 10.1145/962446.962448
XPath is a language for navigating an XML document and selecting a set of element nodes. XPath expressions are used to query XML data, describe key constraints, express transformations, and reference elements in remote documents. This article studies...

From discrepancy to declustering: Near-optimal multidimensional declustering strategies for range queries
Chung-Min Chen, Christine T. Cheng
Pages: 46-73
DOI: 10.1145/962446.962449
Declustering schemes allocate data blocks among multiple disks to enable parallel retrieval. Given a declustering scheme D, its response time with respect to a query Q, rt(Q), is defined to be the maximum number of...

Monadic datalog and the expressive power of languages for Web information extraction
Georg Gottlob, Christoph Koch
Pages: 74-113
DOI: 10.1145/962446.962450
Research on information extraction from Web pages (wrapping) has seen much activity recently (particularly systems implementations), but little work has been done on formally studying the expressiveness of the formalisms proposed or on the...