Mathematical Proceedings of the Cambridge Philosophical Society

Research Article

Free quotients of congruence subgroups of SL2 over a Dedekind ring of arithmetic type contained in a function field

A. W. Masona1

a1 Department of Mathematics, University of Glasgow, Glasgow G1 2 8Q W

Let R be a commutative ring with identity and let q be an ideal in R. For each n xs227D 2, let En(R) be the subgroup of GLn(R) generated by the elementary matrices and let En(R, q) be the normal subgroup of En(R) generated by the q-elementary matrices. We put SLn(R, q) = Ker(SLn(R)SLn(R/q)), the principal congruence subgroup of GLn(R) of level q. (By definition En(R, R) = En(R) and SLn(R, R) = SLn(R).)

(Received May 17 1986)

(Revised September 08 1986)