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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/955

Title: The semijoin algebra and the guarded fragment
Authors: LEINDERS, Dirk
Marx, J.
Tyszkiewicz, J.
VAN DEN BUSSCHE, Jan
Issue Date: 2005
Publisher: Kluwer
Citation: Journal of Logic, Language and Information, 14. p. 331-343
Abstract: In the 1970s Codd introduced the relational algebra, with operators selection, projection, union, difference and product, and showed that it is equivalent to first-order logic. In this paper, we show that if we replace in Codd’s relational algebra the product operator by the “semijoin” operator, then the resulting “semijoin algebra” is equivalent to the guarded fragment of first-order logic. We also define a fixed point extension of the semijoin algebra that corresponds to μGF.
URI: http://hdl.handle.net/1942/955
DOI: 10.1007/s10849-005-5789-8
ISSN: 0925-8531
Category: A2
Type: Journal Contribution
Appears in Collections: Research publications

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