[Settfa] 25 Nov, Zdeněk Silber

[fabian]

Dobrý den pane kolego,

Zatím nevím, zda mki zdraví dovolí přijít na Váš seminář.
Což mě hrozd-ně mrzí.
Takže pokud se tam kolem desáté neobjevím,
tak nečekejte a začněte. A pak bych poprosil mi něco poslat počtou, 
jestli mono.

Ať se tedy zítra daří.

S pozdravem zůstává,
Marián Fabian

ne 2025-11-22 09:00, kubis at math.cas.cz napsal:
> Tuesday, 25 November 2025 - 10:00 to 11:30
> Place: IM, konírna
> 
>  Speaker: Zdeněk Silber, Institute of Mathematics, Czech Academy of
> Sciences
> Title: On subspaces of indecomposable Banach spaces
> 
>  Abstract
> In the talk we adress the following question: What Banach spaces are
> isomorphic to subspaces of indecomposable Banach spaces? Recall that a
> Banach space is indecomposable if it cannot be “decomposed” as a
> direct sum of two infinite dimensional subspaces. A well-known class
> of indecomposable spaces are hereditarily indecomposable spaces, first
> constucted by Gowers and Maurey, but our question makes no sense for
> them, as clearly any subspace of a hereditarily indecomposable space
> is itself hereditarily indecomposable. Hence, we will rather work in
> the class of indecomposable C(K) spaces, introduced by Koszmider.
> Certainly not all spaces can be embedded in an indecomposable space
> – for example l_infinity cannot and neither can any injective space.
> We show that the class of spaces that can be embedded in an
> indecomposable spaces is quite large – it contains all spaces of
> density at most continuum which do not admit l_infinity as a quotient
> (this includes e.g. Asplund or WLD spaces). We also show that there is
> an indecomposable C(K) space that does admit l_infinity as a quotient.
> The general question thus remains open for Banach spaces (of density
> at most continuum) that do admit l_infinity as a quotient but not as a
> subspace.
> 
> This is a joint work with Piotr Koszmider.
> 
>  For more information see the seminar web page at
> https://www.math.cas.cz/index.php/events/seminar/6
> 
>  Set Theory and Analysis mailing list
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> https://list.math.cas.cz/listinfo/settfa@math.cas.cz
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