John C. Meakin

Learn More
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(More)
Birget, J.-C., SW. Margolis and J.C. Meakin, The word problem for inverse monoids presented by one idempotent relator, Theoretical Computer Science 123 (1994) 2733289. We study inverse monoids presented by a finite set of generators and one relation e= I, where e is a word representing an idempotent in the free inverse monoid, and 1 is the empty word. We(More)
We prove that the word problem for the free product with amalgamation S U T of monoids can be undecidable, even when S and T are nitely presented monoids with word problems that are decidable in linear time, the factorization problems for U in each of S and T , as well as other problems, are decidable in polynomial time, and U is a free nitely generated(More)
  • 1