Remarks concerning the freeness problem over morphism and matrix semigroups - UTU Research Portal

A1 Refereed original research article in a scientific journal

Remarks concerning the freeness problem over morphism and matrix semigroups

Authors: Juha Honkala

Publisher: ELSEVIER SCIENCE BV

Publication year: 2014

Journal: Theoretical Computer Science

Journal name in source: THEORETICAL COMPUTER SCIENCE

Journal acronym: THEOR COMPUT SCI

Volume: 557

First page : 115

Last page: 119

Number of pages: 5

ISSN: 0304-3975

DOI: https://doi.org/10.1016/j.tcs.2014.08.013

Abstract

We study the freeness problem over morphism and matrix semigroups. We show that the freeness problem is undecidable for morphisms over a three-letter alphabet. We show that there is a commutative semiring R such that the freeness problem is undecidable for upper-triangular 2 x 2 matrices having entries in R. (C) 2014 Elsevier B.V. All rights reserved.