Proper analytic free maps

Abstract

This paper concerns analytic free maps. These maps are free analogs of classical analytic functions in several complex variables, and are defined in terms of non-commuting variables amongst which there are no relations – they are free variables. Analytic free maps include vector-valued polynomials in free (non-commuting) variables and form a canonical class of mappings from one non-commutative domain D in say g variables to another non-commutative domain D ˜ in g ˜ variables. As a natural extension of the usual notion, an analytic free map is proper if it maps the boundary of D into the boundary of D ˜ . Assuming that both domains contain 0, we show that if f : D → D ˜ is a proper analytic free map, and f ( 0 ) = 0 , then f is one-to-one. Moreover, if also g = g ˜ , then f is invertible and f − 1 is also an analytic free map. These conclusions on the map f are the strongest possible without additional assumptions on the domains D and D ˜ .