Zobrazeno 1 - 10
of 76
pro vyhledávání: '"Kochanek, Tomasz"'
Autor:
Kochanek, Tomasz, Miarka, Marek
We show that if a separable Banach space has Kalton's property $(M^\ast)$, then all $\varepsilon$-Szlenk derivations of the dual unit ball are balls, however, in the case of the dual of Baernstein's space, all those Szlenk derivations are balls havin
Externí odkaz:
http://arxiv.org/abs/2409.05516
Autor:
Kochanek, Tomasz
We study operator semigroups in the Calkin algebra $\mathcal{Q}(\mathcal{H})$, represented as a subalgebra of the algebra of bounded linear operators on a Hilbert space via one of `canonical' Calkin's representations. Using the BDF theory, we associa
Externí odkaz:
http://arxiv.org/abs/2403.17956
Autor:
Kochanek, Tomasz, Miarka, Marek
For Banach spaces with a shrinking FDD, we provide estimates for the radii of the enveloping balls of the $\varepsilon$-Szlenk derivations of the dual unit ball.
Externí odkaz:
http://arxiv.org/abs/2403.07085
Autor:
Kochanek, Tomasz
For a discrete group $G$, we consider certain ideals $\mathcal{I}\subset c_0(G)$ of sequences with prescribed rate of convergence to zero. We show that the equality between the full group C$^\ast$-algebra of $G$ and the C$^\ast$-completion $\mathrm{C
Externí odkaz:
http://arxiv.org/abs/2403.06945
Autor:
Kochanek, Tomasz
We prove an Ulam type stability result for a non-associative version of the multiplicativity equation, that is, $T(xy)=\Psi(T(x),T(y))$, where $T$ is a unital bounded operator acting from an amenable Banach algebra to a dual Banach algebra.
Comm
Comm
Externí odkaz:
http://arxiv.org/abs/2303.07869
Autor:
Kochanek, Tomasz
We study lifting problems for operator semigroups in the Calkin algebra $\mathscr{Q}(\mathcal{H})$, our approach being mainly based on the Brown--Douglas--Fillmore theory. With any normal $C_0$-semigroup $(q(t))_{t\geq 0}$ in $\mathscr{Q}(\mathcal{H}
Externí odkaz:
http://arxiv.org/abs/2203.05635
Autor:
Kochanek, Tomasz
We investigate linear operators between C$^\ast$-algebras which approximately preserve involution and orthogonality, the latter meaning that for some $\varepsilon>0$ we have $\|\phi(x)\phi(y)\|\leq\varepsilon\|x\|\|y\|$ for all positive $x,y$ with $x
Externí odkaz:
http://arxiv.org/abs/1911.01689
We introduce asymptotic analogues of the Rademacher and martingale type and cotype of Banach spaces and operators acting on them. Some classical local theory results related, for example, to the `automatic-type' phenomenon, the type-cotype duality, o
Externí odkaz:
http://arxiv.org/abs/1712.04208
We prove two results concerning an Ulam-type stability problem for homomorphisms between lattices. One of them involves estimates by quite general error functions; the other deals with approximate (join) homomorphisms in terms of certain systems of l
Externí odkaz:
http://arxiv.org/abs/1712.03513
Lipschitz-free spaces over compact subsets of superreflexive spaces are weakly sequentially complete
Autor:
Kochanek, Tomasz, Pernecká, Eva
Let $M$ be a compact subset of a superreflexive Banach space. We prove that the Lipschitz-free space $\mathcal{F}(M)$, the predual of the Banach space of Lipschitz functions on $M$, has the Pe{\l}czy\'nski's property ($V^\ast$). As a consequence, the
Externí odkaz:
http://arxiv.org/abs/1703.07896