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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/7740

Title: Structural Recursion on Ordered Trees and List-Based Complex Objects
Authors: ROBERTSON, Edward L.
Issue Date: 2007
Publisher: Springer
Citation: Database Theory - ICDT 2007. p. 344-358
Series/Report: Lecture Notes in Computer Science, 4353
Abstract: XML query languages need to provide some mechanism to inspect and manipulate nodes at all levels of an input tree. In this paper we investigate the expressive power provided in this regard by structural recursion. We show that the combination of vertical recursion down a tree combined with horizontal recursion across a list of trees gives rise to a robust class of transformations: it captures the class of all primitive recursive queries. Since queries are expected to be computable in at most polynomial time for all practical purposes, we next identify a restriction of structural recursion that captures the polynomial time queries. Although this restriction is semantical in nature, and therefore undecidable, we provide an effective syntax. We also give corresponding results for list-based complex objects.
URI: http://hdl.handle.net/1942/7740
DOI: 10.1007/11965893_24
ISI #: 000244800500024
ISBN: 3-540-69269-X
ISSN: 1611-3349
Category: C1
Type: Proceedings Paper
Appears in Collections: Research publications

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