A note on Ottmar Loos' paper "Remarks on Holger P. Petersson's 'Idempotent 2 by 2 matrices' "
In his recent note on a paper by Holger P. Petersson, Ottmar
Loos determines the invertible elements in a Laurent polynomial ring
k[t,t^{-1}] over an arbitrary commutative associative unital ring k (see
the previous two papers). In this note, this is generalized to the
setting where the Laurent polynomial ring is replaced by the group
algebra k[G] of an ordered group G.
(Updated version 8 Oct 2008, to appear in Acta Appl. Math. under the title
"Invertible and nilpotent elements in the group
algebra of a unique product group")
E. Neher < Erhard.Neher@uottawa.ca >