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 language | English (US) |
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Pages (from-to) | 247-281 |
Number of pages | 35 |
Journal | Theoretical Computer Science |
Volume | 242 |
Issue number | 1-2 |
DOIs | |
State | Published - Jul 6 2000 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Theoretical Computer Science
- General Computer Science
Keywords
- Inverse automata
- PSPACE-completeness
- Pure subgroups
- Subgroups of the free group