Computational Algebra Seminar: Kirschmer -- The explicit membership problem for discrete free subgroup of PSL(2,R)

Speaker: Markus Kirschmer
Title: The explicit membership problem for discrete free subgroup of PSL(2,R)
Time & Place: 3:05-4pm, Thursday 1 November, Carslaw 535

Abstract:
Computing with matrix groups over infinite rings is much more complicated then
working with matrix groups over finite fields.

For example, the membership problem is undecidable in general.

However, for subgroups of \PSL(2, \R) the situation is much better since we have
geometric methods at hand.


In this talk, we will recall Rosenberger’s classification of the discrete free
subgroups G = < A, B> of \PSL(2,\R).
Further, we will discuss how to solve the membership problem for such a group G
constructively.
This is joint work with B. Eick and C. Leedham-Green.