A large scale approach to decomposition spaces

Abstract

Decomposition spaces are a class of function spaces constructed out of “well-behaved” coverings and partitions of unity of a set. The structure of the covering determines the properties of the decomposition space. Besov spaces, shearlet spaces, and modulation spaces are well-known decomposition spaces. In this paper, we focus on the geometric aspects of decomposition spaces and utilize that these are naturally captured by the large scale properties of a metric space associated to the covering. We demonstrate that decomposition spaces constructed out of quasi-isometric covered spaces have many geometric features in common.

The notion of geometric embedding is introduced to formalize the way one decomposition space can be embedded into another decomposition space while respecting the geometric features of the coverings. Some consequences of the large scale approach to decomposition spaces are (i) the comparison of coverings of different sets, (ii) the study of embeddings of decomposition spaces based on the geometric features and the symmetries of the coverings, and (iii) the use of notions from large scale geometry, such as asymptotic dimension or hyperbolicity, to study the properties of decomposition spaces.