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arXiv · 1510.04881

Linear Context-Free Tree Languages and Inverse Homomorphisms

Johannes Osterholzer·Toni Dietze·Luisa Herrmann
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Abstract

We prove that the class of linear context-free tree languages is not closed under inverse linear tree homomorphisms. The proof is by contradiction: we encode Dyck words into a context-free tree language and prove that its preimage under a certain linear tree homomorphism cannot be generated by any context-free tree grammar. A positive result can still be obtained: the linear monadic context-free tree languages are closed under inverse linear tree homomorphisms.

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Johannes Osterholzer, Toni Dietze, Luisa Herrmann. 2015-10-16. Linear Context-Free Tree Languages and Inverse Homomorphisms. https://arxiv.org/abs/1510.04881

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