Published online by Cambridge University Press: 20 November 2018
Let PGL(2, ƒ) denote the group of all Moebius transformations
over a field F. The object of this paper is to prove the following theorem.
Theorem 1. G is an S2-group and the centre of G is trivial if and only if G is isomorphic to a group PGL(2, ƒ), char ƒ ≠ 2.
This theorem was proved for finite groups in (1). The present paper extends the result to infinite groups and also improves the method of proof used in that paper. Many of the theorems given there were proved for infinite groups and are used here with appropriate references.