On the Equivalence Checking Problem for Deterministic Top-Down Tree Automata

Fuente: arXiv
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Main Authors: Deng, Zhibo, Zakharov, Vladimir A.
Format: Preprint
Published: 2025
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author Deng, Zhibo
Zakharov, Vladimir A.
author_facet Deng, Zhibo
Zakharov, Vladimir A.
contents We present an efficient algorithm for checking language equivalence of states in top-down deterministic finite tree automata (DFTAs). Unlike string automata, tree automata operate over hierarchical structures, posing unique challenges for algorithmic analysis. Our approach reduces the equivalence checking problem to that of checking the solvability of a system of language-theoretic equations, which specify the behavior of a DFTA. By constructing such a system of equations and systematically manipulating with it through substitution and conflict detection rules, we develop a decision procedure that determines whether two states accept the same tree language. We formally prove the correctness and termination of the algorithm and establish its worst-case time complexity as $O(n^2)$ under the RAM (Random Access Machine) model of computation augmented with pointers.
format Preprint
id arxiv_https___arxiv_org_abs_2504_04206
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Equivalence Checking Problem for Deterministic Top-Down Tree Automata
Deng, Zhibo
Zakharov, Vladimir A.
Formal Languages and Automata Theory
Logic
68Q45
F.4.3
We present an efficient algorithm for checking language equivalence of states in top-down deterministic finite tree automata (DFTAs). Unlike string automata, tree automata operate over hierarchical structures, posing unique challenges for algorithmic analysis. Our approach reduces the equivalence checking problem to that of checking the solvability of a system of language-theoretic equations, which specify the behavior of a DFTA. By constructing such a system of equations and systematically manipulating with it through substitution and conflict detection rules, we develop a decision procedure that determines whether two states accept the same tree language. We formally prove the correctness and termination of the algorithm and establish its worst-case time complexity as $O(n^2)$ under the RAM (Random Access Machine) model of computation augmented with pointers.
title On the Equivalence Checking Problem for Deterministic Top-Down Tree Automata
topic Formal Languages and Automata Theory
Logic
68Q45
F.4.3
url https://arxiv.org/abs/2504.04206