Greedy bases are best for m-term approximation
نویسنده
چکیده
We study the approximation of a subset K in a Banach space X by choosing first basis B and then using n-term approximation. Into the competition for best bases we enter all unconditional bases for X. We show that if the subset K ⊂ X is well aligned with respect to a greedy basis B then, in certain sense, this basis is the best for this type of approximation. Our result extends the recent result of DeVore, Petrowa and Temlyakov.
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