For a unital C*-algebra 21 with unit ball 911 the set (￡ of extreme points in consists of elements V in S2li, necessarily partial isometries, such that cf. [15] or [21, 1.4.7]. In [8] we defined the set of quasi-invertible elements in <2I as and showed that this is an appropriate concept for infinite C*-algebras, re-placing to a certain extent the group 9l~' of invertible elements. In particular we studied the class of extremally rich C*-algebras, i.e. C*-algebras 91 for which 9l~' is dense, as an analogue of Rieffel's stable rank one algebras. In this paper we use the distance function.
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