Classifying decomposition and wavelet coorbit spaces using coarse geometry

Abstract

This paper is concerned with the study of Besov-type decomposition spaces, which are scales of spaces associated to suitably defined coverings of the euclidean space Rd, or suitable open subsets thereof. A fundamental problem in this domain, that is currently not fully understood, is deciding when two different coverings give rise to the same scale of decomposition spaces.In this paper, we establish a coarse geometric approach to this problem, and show how it specializes for the case of wavelet coorbit spaces associated to a particular class of matrix groups H<GL(Rd) acting via dilations. These spaces can be understood as special instances of decomposition spaces, and it turns out that the question whether two different dilation groups H1,H2 have the same coorbit spaces can be decided by investigating whether a suitably defined map ϕ:H1→H2 is a quasi-isometry with respect to suitably defined word metrics. We then proceed to apply this criterion to a large class of dilation groups called shearlet dilation groups, where this quasi-isometry condition can be characterized algebraically. We close with the discussion of selected examples.