English

Groups with ALOGTIME-hard word problems and PSPACE-complete compressed word problems

Group Theory 2020-06-23 v5 Computational Complexity

Abstract

We give lower bounds on the complexity of the word problem of certain non-solvable groups: for a large class of non-solvable infinite groups, including in particular free groups, Grigorchuk's group and Thompson's groups, we prove that their word problem is NC1\mathsf{NC}^1-hard. For some of these groups (including Grigorchuk's group and Thompson's groups) we prove that the compressed word problem (which is equivalent to the circuit evaluation problem) is PSPACE\mathsf{PSPACE}-complete.

Keywords

Cite

@article{arxiv.1909.13781,
  title  = {Groups with ALOGTIME-hard word problems and PSPACE-complete compressed word problems},
  author = {Laurent Bartholdi and Michael Figelius and Markus Lohrey and Armin Weiß},
  journal= {arXiv preprint arXiv:1909.13781},
  year   = {2020}
}

Comments

A short version of the paper will appear in the Proceedings of the Computational Complexity Conference 2020

R2 v1 2026-06-23T11:30:26.384Z