Approximation of Besov vectors by Paley-Wiener vectors in Hilbert spaces
  We develop an approximation theory in Hilbert spaces that generalizes the classical theory of approximation by entire functions of exponential type. The results advance harmonic analysis on manifolds and graphs, thus facilitating data representation, compression, denoising and visualization. These tasks are of great importance to machine learning, complex data analysis and computer vision. 
Isaac Z. Pesenson, Meyer Z. Pesenson
math.FA