Fractional Sobolev spaces related to an ultraparabolic operator
摘要
We propose a functional framework of fractional Sobolev spaces for a class of ultraparabolic Kolmogorov-type operators satisfying the weak Hörmander condition. We characterize these spaces as real interpolation of natural-order intrinsic Sobolev spaces recently introduced in Pascucci and Pesce (J Funct Anal 286(7):Paper No. 110344, 40, 2024) and prove continuous embeddings into