On Asymptotically Orthonormal Sequences
  An asymptotically orthonormal sequence is a sequence which is 'nearly' orthonormal in the sense that it satisfies the Parseval equality up to two constants close to one. In this paper, we explore such sequences formed by normalized reproducing kernels of model spaces and de Branges Rovnyak spaces. 
Emmanuel Fricain and Rishika Rupam
math.CV