Node Selection Query Languages for Trees

Diego Calvanese, Giuseppe De Giacomo, Maurizio Lenzerini, and Moshe Y. Vardi

Proc. of the 24th AAAI Conf. on Artificial Intelligence (AAAI 2010). 2010.

The study of node-selection query languages for (finite) trees has been a major topic in the recent research on query langauges for Web documents. On one hand, there has been an extensive study of XPath and its various extensions. On the other hand, query languages based on classical logics, such as first-order logic (FO) or monadic second-order logic (MSO), have been considered. Results in this area typically relate an Xpath-based language to a classical logic. What has yet to emerge is an XPath-related language that is both expressive as MSO, while at the same times enjoys the computational properties of XPath, which are linear query evaluation and exponential query-containment test. In this paper we propose mu-XPath, which is the alternation-free fragment of XPath extended with fixpoint operators. Using two-way alternating automata, we show that this language does combine desired expressiveness and computational properties, placing it as an attractive candidate as the definite query language for trees.

   title = "Node Selection Query Languages for Trees",
   year = "2010",
   author = "Diego Calvanese and De Giacomo, Giuseppe and Maurizio
Lenzerini and Moshe Y. Vardi",
   booktitle = "Proc. of the 24th AAAI Conf. on Artificial Intelligence
(AAAI 2010)",
   pages = "279--284",
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