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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/13198

Title: Relative expressive power of navigational querying on graphs
Authors: Fletcher, George H. L.
Gyssens, Marc
Leinders, Dirk
Van den Bussche, Jan
Van Gucht, Dirk
Vansummeren, Stijn
Wu, Yuqing
Issue Date: 2011
Publisher: ACM Press
Citation: Milo, Tova (Ed.). Database Theory - ICDT 2011, 14th International Conference, Uppsala, Sweden, March 21-24, 2011, Proceedings, ACM Press,p. 197-207
Abstract: Motivated by both established and new applications, we study navigational query languages for graphs (binary relations). The simplest language has only the two operators union and composition, together with the identity relation. We make more powerful languages by adding any of the following operators: intersection; set di erence; projection; coprojection; converse; transitive closure; and the diversity relation. All these operators map binary relations to binary relations. We compare the expressive power of all resulting languages. We do this not only for general path queries (queries where the result may be any binary relation) but also for boolean or yes/no queries (expressed by the nonemptiness of an expression). For both cases, we present the complete Hasse diagram of relative expressiveness. In particular, the Hasse diagram for boolean queries contains nontrivial separations and a few surprising collapses.
URI: http://hdl.handle.net/1942/13198
DOI: 10.1145/1938551.1938578
ISBN: 978-1-4503-0529-7
Category: C1
Type: Proceedings Paper
Appears in Collections: Research publications

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