On some characterizations of greedy-type bases

synthesis and characterization of some macrocyclic schiff bases

ماکروسیکلهای شیف باز از اهمیت زیادی در شیمی آلی و دارویی برخوردار می باشند. این ماکروسیکلها با دارابودن گروه های مناسب در مکانهای مناسب می توانند فلزاتی مثل مس، نیکل و ... را در حفره های خود به دام انداخته، کمپلکسهای پایدار تولید نمایند. در این پایان نامه ابتدا یک دی آلدئید آروماتیک از گلیسیرین تهیه می شود و در مرحله بعدی واکنش با دی آمینهای آروماتیک و یا آلیفاتیک در رقتهای بسیار زیاد منجر به ت...

Lebesgue-type Inequalities for Quasi-greedy Bases

We show that for quasi-greedy bases in real or complex Banach spaces the error of the thresholding greedy algorithm of order N is bounded by the best N term error of approximation times a function of N which depends on the democracy functions and the quasi-greedy constant of the basis. If the basis is democratic this function is bounded by C logN . We show with two examples that this bound is a...

Lebesgue-type Inequalities for Quasi-greedy Bases

New characterizations of fusion bases and Riesz fusion bases in Hilbert spaces

In this paper we investigate a new notion of bases in Hilbert spaces and similar to fusion frame theory we introduce fusion bases theory in Hilbert spaces. We also introduce a new denition of fusion dual sequence associated with a fusion basis and show that the operators of a fusion dual sequence are continuous projections. Next we dene the fusion biorthogonal sequence, Bessel fusion basis, Hil...

New Characterizations of Riesz Bases

Various equivalent conditions under which a frame is a Riesz basis of a separable Hilbert space are known. See [8] among others, for instance. We add two new conditions to the list. They are inspired by the projection method proposed in [2], which approximates frame coefficients by using finite subsets of a frame. Our main approach is to transcribe anything involving a frame in a Hilbert space ...