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- Murray Elder, Mark Kambites, Gretchen Ostheimer
- IJAC
- 2008

We study finitely generated groups whose word problems are accepted by counter automata. We show that a group has word problem accepted by a blind n-counter automaton in the sense of Greibach if andâ€¦ (More)

Counter automata are more powerful versions of finitestate automata where addition and subtraction operations are permitted on a set of n integer registers, called counters. We show that the wordâ€¦ (More)

- Gillian Z. Elston, Gretchen Ostheimer
- Theor. Comput. Sci.
- 2004

We prove that a group G has a word problem that is accepted by a deterministic counter automaton with a weak inverse property if and only if G is virtually abelian. We extend this result to largerâ€¦ (More)

- Bettina Eick, Gretchen Ostheimer
- Math. Comput.
- 2003

We present an algorithm to solve the orbit-stabilizer problem for a polycyclic group G acting as a subgroup of GL(d,Z) on the elements of Qd. We report on an implementation of our method and use thisâ€¦ (More)

- Gretchen Ostheimer
- J. Symb. Comput.
- 1999

Many fundamental problems are undecidable for in nite matrix groups. Polycyclic matrix groups represent a large class of groups for which these same problems are known to be decidable. In this paperâ€¦ (More)

- Murray Elder, Gillian Z. Elston, Gretchen Ostheimer
- ArXiv
- 2012

Article history: Received 20 January 2012 Available online 26 February 2013 Communicated by Derek Holt

- Eddie H. Lo, Gretchen Ostheimer
- J. Symb. Comput.
- 1999

We describe a new algorithm for nding matrix representations for polycyclic groups given by nite presentations. In contrast to previous algorithms, our algorithm is e cient enough to constructâ€¦ (More)

- Gretchen Ostheimer
- Groups and Computation
- 1995

Let K be a number eld. We present several algorithms for working with polycyclic-by-nite subgroups of GL(n; K). Let G be a subgroup of GL(n; K) given by a nite generatingset of matrices. We describeâ€¦ (More)

OF THE DISSERTATION Algorithms for Polycyclic-by-Finite Groups by Gretchen Ostheimer Dissertation Director: Professor Charles C. Sims Let R be a number eld. We present several algorithms for workingâ€¦ (More)

In 1954 A. G. Howson proved that the intersection of two finitely generated subgroups of a free group is again finitely generated. Now the free metabelian subgroups of a free metabelian group ofâ€¦ (More)