Mathematical Proceedings of the Cambridge Philosophical Society

Research Article

Amalgamation and the invariant trace field of a Kleinian group

Walter D. Neumanna1 and Alan W. Reida1

a1 Department of Mathematics, Ohio State University, 231 West 18th Avenue, Columbus OH 43210-1174, U.S.A.

Let Γ be a Kleinian group of finite covolume and denote by Γ(2) the subgroup generated by {γ2xs2208 Γ}. In [9] the trace field of Γ(2) was shown to be an invariant of the commensurability class of Γ. In [8] this field was termed the invariant trace field of Γ and further properties of this field were studied. Following the notation of [8] we denote the invariant trace field of Γ by k(Γ).

(Received June 04 1990)

(Revised July 03 1990)