Weighted HOM-Problem for Nonnegative Integers

Abstract

The HOM-problem asks whether the image of a regular tree language under a given tree homomorphism is again regular. It was recently shown to be decidable by Godoy, Gim\'enez, Ramos, and \`Alvarez. In this paper, the N-weighted version of this problem is considered and its decidability is proved. More precisely, it is decidable in polynomial time whether the image of a regular N-weighted tree language under a nondeleting, nonerasing tree homomorphism is regular.