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A decidable characterization of locally testable tree languages (1109.5851v2)
Published 27 Sep 2011 in cs.FL
Abstract: A regular tree language L is locally testable if membership of a tree in L depends only on the presence or absence of some fix set of neighborhoods in the tree. In this paper we show that it is decidable whether a regular tree language is locally testable. The decidability is shown for ranked trees and for unranked unordered trees.