Explicit representation of terms defined by counter examples
Journal of Automated Reasoning
Equational formulae with membership constraints
Information and Computation
Undecidable properties of deterministic top-down tree transducers
Theoretical Computer Science
Decidability of regularity and related properties of ground normal form languages
Information and Computation
Handbook of formal languages, vol. 3
ACM SIGMOD Record
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
On the complexity of typechecking top-down XML transformations
Theoretical Computer Science - Database theory
Taxonomy of XML schema languages using formal language theory
ACM Transactions on Internet Technology (TOIT)
Proceedings of the forty-second ACM symposium on Theory of computing
The HOM Problem is EXPTIME-Complete
LICS '12 Proceedings of the 2012 27th Annual IEEE/ACM Symposium on Logic in Computer Science
Journal of the ACM (JACM)
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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.