Abstract
We study visibly pushdown automata (VPA) models for expressing and evaluating queries on words with a nesting structure. We define a query VPA model, which is a 2-way deterministic VPA that can mark in one run all positions in a document that satisfy a query, and show that it is equi-expressive as unary monadic queries. This surprising result parallels a classic result by Hopcroft and Ullman for queries on regular word languages. We also compare our model to query models on unranked trees, and show that our result is fundamentally different from those known for automata on trees. © 2009 Springer Berlin Heidelberg.
Cite
CITATION STYLE
Madhusudan, P., & Viswanathan, M. (2009). Query automata for nested words. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 5734 LNCS, pp. 561–573). https://doi.org/10.1007/978-3-642-03816-7_48
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