Deciding Equivalence of Linear Tree-to-Word Transducers in Polynomial Time

TL;DR

This paper proves that determining whether two deterministic linear top-down tree-to-word transducers are equivalent can be done efficiently in polynomial time, advancing understanding of XML and document transformation models.

Contribution

It introduces a polynomial-time decision procedure for equivalence of deterministic linear top-down tree-to-word transducers using a new partial normal form.

Findings

Equivalence is decidable in polynomial time.

A partial normal form characterizes the languages produced.

Applicable to XML and document transformation tasks.

Abstract

We show that the equivalence of deterministic linear top-down tree-to-word transducers is decidable in polynomial time. Linear tree-to-word transducers are non-copying but not necessarily order-preserving and can be used to express XML and other document transformations. The result is based on a partial normal form that provides a basic characterization of the languages produced by linear tree-to-word transducers.