O. Davydov, M. Sommer and H. Strauss, On almost interpolation and locally linearly independent bases, East J. Approx. 5 (1999), 67-88.

Abstract: A characterization of almost interpolation configurations of points in terms of supports of basis functions is presented. Moreover, we show that this characterization can be significantly simplified in the case of existence of a locally linearly independent basis, so that almost interpolation sets can be constructed by taking a point in a support of each basis function. Some further results, including several equivalent definitions of a locally linearly independent system of functions, are given.

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