A Classification Theorem on Non-compact Embeddings between Besov Spaces

We analyze the embedding properties between Besov spaces, defined on the total space ${\mathbb{R}}^n$ and on bounded domains. We give a complete classification on whether or not these embedding maps satisfy certain weak compactness characterized by the so-called strictly and finitely strictly singular condition. The result extends the recent findings on Sobolev embeddings by offering a refined description of the quality of non-compactness in the setting of Besov spaces.