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Tanmoy Paul
  • Member for 9 years, 4 months
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Finding the set of best approximation
Nonemptyness of $J_X(f)$.
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Finding the set of best approximation
Yes. I was under impression a Frechet smooth point would also be an SSD point. Check Proposition 3.1 from the paper by Indumathi & Lalithambigai. For those points $x$, when $d(x,Y)=d(x,B_Y)$ one can have some cases when $P_{B_Y}(x)$ is nonempty or empty.
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Finding the set of best approximation
It is wrong. $J_X(f)$ is a singleton.
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Finding the set of best approximation
Slight modification is needed in my last statement. For a point $x\in \ell_1$, $\inf\{\|y\|:y\in P_Y(x)\}\leq 1$ if and only if $d(x,Y)=d(x,B_Y)$. Here $Y$ is as stated above.
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Finding the set of best approximation
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revised
Finding the set of best approximation
added 93 characters in body
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The Schur property and containing no isomorphic copy of $l_{1}$
This is related to the first comment made by Narutaka; any separable Banach space can be embedded inside $\ell_\infty$.
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On weak Hahn-Banach smoothness
This is 'Best approximation and intersection properties of balls' by David Yost, appeared in Bull Aust Math Soc (1979)
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Renorming of $C[0,1]$ for a strictly convex dual
My earlier question can be reformulated as follows. Does there exist an equivalent renorming on $C[0,1]$ which makes it (weakly) Hahn-Banach smooth? Probably the answer to this problem is 'No' because the dual of any weakly Hahn-Banach smooth space has RNP.