Page 1 Next

Displaying 1 – 20 of 490

Showing per page

A bilinear version of Holsztyński's theorem on isometries of C(X)-spaces

Antonio Moreno Galindo, Ángel Rodríguez Palacios (2005)

Studia Mathematica

We prove that, for a compact metric space X not reduced to a point, the existence of a bilinear mapping ⋄: C(X) × C(X) → C(X) satisfying ||f⋄g|| = ||f|| ||g|| for all f,g ∈ C(X) is equivalent to the uncountability of X. This is derived from a bilinear version of Holsztyński's theorem [3] on isometries of C(X)-spaces, which is also proved in the paper.

A characterization of regular averaging operators and its consequences

Spiros A. Argyros, Alexander D. Arvanitakis (2002)

Studia Mathematica

We present a characterization of continuous surjections, between compact metric spaces, admitting a regular averaging operator. Among its consequences, concrete continuous surjections from the Cantor set 𝓒 to [0,1] admitting regular averaging operators are exhibited. Moreover we show that the set of this type of continuous surjections from 𝓒 to [0,1] is dense in the supremum norm in the set of all continuous surjections. The non-metrizable case is also investigated. As a consequence, we obtain...

A C(K) Banach space which does not have the Schroeder-Bernstein property

Piotr Koszmider (2012)

Studia Mathematica

We construct a totally disconnected compact Hausdorff space K₊ which has clopen subsets K₊” ⊆ K₊’ ⊆ K₊ such that K₊” is homeomorphic to K₊ and hence C(K₊”) is isometric as a Banach space to C(K₊) but C(K₊’) is not isomorphic to C(K₊). This gives two nonisomorphic Banach spaces (necessarily nonseparable) of the form C(K) which are isomorphic to complemented subspaces of each other (even in the above strong isometric sense), providing a solution to the Schroeder-Bernstein problem for Banach spaces...

A formula for the Bloch norm of a C 1 -function on the unit ball of n

Miroslav Pavlović (2008)

Czechoslovak Mathematical Journal

For a C 1 -function f on the unit ball 𝔹 n we define the Bloch norm by f 𝔅 = sup d ˜ f , where d ˜ f is the invariant derivative of f , and then show that f 𝔅 = sup z , w 𝔹 z w ( 1 - | z | 2 ) 1 / 2 ( 1 - | w | 2 ) 1 / 2 | f ( z ) - f ( w ) | | w - P w z - s w Q w z | .

Currently displaying 1 – 20 of 490

Page 1 Next