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2010
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Forward-XPath and extended register automata on data-trees

10 years 7 months ago
Forward-XPath and extended register automata on data-trees
We consider a fragment of XPath named `forward-XPath', which contains all descendant and rightwards sibling axes as well as data equality and inequality tests. The satisfiability problem for forward-XPath in the presence of DTDs and even of primary key constraints is shown here to be decidable. To show decidability we introduce a model of alternating automata on data trees that can move downwards and rightwards in the tree, have one register for storing data and compare them for equality, and have the ability to (1) nondeterministically guess a data value and store it, and (2) quantify universally over the set of data values seen so far during the run. This model extends the work of Jurdzi?nski and Lazi?c. Decidability of the finitary non-emptiness problem for this model is obtained by a direct reduction to a well-structured transition system, contrary to previous approaches. Categories and Subject Descriptors I.7.2 [Document Preparation]: Markup Languages ; H.2.3 [Database Manag...
Diego Figueira
Added 01 Mar 2010
Updated 02 Mar 2010
Type Conference
Year 2010
Where ICDT
Authors Diego Figueira
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