Tseng

Infinite Projections in Full Group C*-Algebras of S-Arithmetic Groups

Let K be a number field, let Σ be a nonempty finite set of nonzero prime ideals of O_K, and let n ≥ 4. We prove that C*max(SL_n(O_{K,Σ})) contains an infinite projection and a proper isometry. Hence it is not finite and is neither stably finite nor MF, although SL_n(O_{K,Σ}) is a...