English

The word problem for free groups cannot be solved in linear time*

Group Theory 2022-02-14 v1 Combinatorics

Abstract

*by a standard (one-tape) Turing machine. It is well-known that the word problem for hyperbolic groups, whence in particular for free groups, can be solved in linear time. However, these algorithms run on machines more complicated than a standard Turing machine. By contrast, in this note we show that a standard Turing machine cannot solve the word problem for the free group on two generators in less than quadratic time.

Cite

@article{arxiv.2202.05787,
  title  = {The word problem for free groups cannot be solved in linear time*},
  author = {Alessandro Sisto},
  journal= {arXiv preprint arXiv:2202.05787},
  year   = {2022}
}

Comments

2 pages

R2 v1 2026-06-24T09:32:32.723Z