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Conference Papers Year : 2008

Classes of Tree Homomorphisms with Decidable Preservation of Regularity

Abstract

Decidability of regularity preservation by a homomorphism is a well known open problem for regular tree languages. Two interesting subclasses of this problem are considered: first, it is proved that regularity preservation is decidable in polynomial time when the domain language is constructed over a monadic signature, i.e., over a signature where all symbols have arity 0 or 1. Second, decidability is proved for the case where non-linearity of the homomorphism is restricted to the root node (or nodes of bounded depth) of any input term. The latter result is obtained by proving decidability of this problem: Given a set of terms with regular constraints on the variables, is its set of ground instances regular? This extends previous results where regular constraints where not considered.
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Dates and versions

hal-00243123 , version 1 (06-02-2008)

Identifiers

  • HAL Id : hal-00243123 , version 1

Cite

Guillem Godoy, Sebastian Maneth, Sophie Tison. Classes of Tree Homomorphisms with Decidable Preservation of Regularity. FOSSACS'08, Apr 2008, Hungary. pp.127-141. ⟨hal-00243123⟩
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