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摘要
Let A subset of R be a uniformly discrete sequence and S subset of R a compact set. It is proved that if there exists a bounded sequence of functions in the Paley Wiener space PWs that approximates delta-functions on A with l(2)-error d, then the measure of S cannot be less than 2 pi(1-d(2))D(+)(Lambda). This estimate is sharp for every d. A similar estimate holds true when the norms of the approximating functions have a moderate growth; the corresponding sharp growth restriction is found.
- 出版日期2010-12
