An Inequality for Bi-orthogonal Pairs
نویسنده
چکیده
We use Salem’s method [13, 14] to prove an inequality of Kwapień and Pełczyński concerning a lower bound for partial sums of series of bi-orthogonal vectors in a Hilbert space, or the dual vectors. This is applied to some lower bounds on L norms for orthogonal expansions.
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