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3 votes
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Non uniqueness of center of the Banach-Mazur compactum

In "The Banach-Mazur distance to the cube and the Dvoretzky-Rogers factorization" Szarek and Bourgain prove a proportional Dvoretzky-Rogers factorization : Given $1>\delta>0$ , there ...
Gericault's user avatar
  • 245
3 votes
0 answers
173 views

A Caratheodory-like result for infinite-dimensional simplices

Let $K$ be a compact metric space; $\Delta K$ be the set of Borel probability measures on $K$ endowed with the weak* topology; $X$ be a closed subset of $\Delta K$; and $x_0 \in \overline{\text{co}} X$...
e.lipnowski's user avatar
2 votes
0 answers
109 views

Quotient Banach space whose dual map sends the ball onto a given convex subset

Let $X$ be a Banach space and let $A$ be a closed, convex and balanced subset of $B_{X^{*}}$ (where $B_{X^{*}}$ denotes the closed unit ball of the dual $X^{*}$). Is there a closed subspace $M$ of $X$ ...
Dongyang Chen's user avatar
1 vote
0 answers
439 views

Does the dual Banach space $B(\ell^\infty)$ have weak* normal structure?

Let $K$ be a bounded closed convex subset of a Banach space $E$. A point $x$ in $K$ is called a diametral point if $$ \sup_{y\in K} \|x-y\|={\rm diam}(K). $$ where ${\rm diam}(K)$ denotes the ...
BigBill's user avatar
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0 votes
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56 views

Zero flux along lines

I am considering the $L^1$ ball in $\mathbb{R}^d$, and a conservative vector field $V$ on it, which arises as the gradient of a bounded, almost-everywhere Lipchitz-function. Denoting by $e_i$ as the i’...
Brendan Mallery's user avatar