All Questions
5 questions with no upvoted or accepted answers
3
votes
0
answers
145
views
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 ...
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 $x_0 \in \overline{\text{co}} X$...
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 $X$ ...
1
vote
0
answers
439
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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 ...
0
votes
0
answers
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’...