Type: Seminar

Distribution: World

Expiry: 1 Nov 2012

Auth: billu@daumier.maths.usyd.edu.au

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.