PSPACE-complete problems for subgroups of free groups and inverse finite automata

J. C. Birget, S. Margolis, J. Meakin, P. Weil

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

We investigate the complexity of algorithmic problems on finitely generated subgroups of free groups. Margolis and Meakin showed how a finite monoid Synt(H) can be canonically and effectively associated with such a subgroup H. We show that H is pure (that is, closed under radical) if and only if Synt(H) is aperiodic. We also show that testing for this property of H is PSPACE-complete. In the process, we show that certain problems about finite automata which are PSPACE-complete in general remain PSPACE-complete when restricted to injective and inverse automata (with single accept state), whereas they are known to be in NC for permutation automata (with single accept state).

Original languageEnglish (US)
Pages (from-to)247-281
Number of pages35
JournalTheoretical Computer Science
Volume242
Issue number1-2
DOIs
StatePublished - Jul 6 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science

Keywords

  • Inverse automata
  • PSPACE-completeness
  • Pure subgroups
  • Subgroups of the free group

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