Schauder Bases in Banach Spaces of Continuous Functions

  • PDF / 7,311,235 Bytes
  • 142 Pages / 461 x 684 pts Page_size
  • 78 Downloads / 229 Views

DOWNLOAD

REPORT


918

Zbigniew Semadeni

Schauder Bases in Banach Spaces of Continuous Functions

Springer-Verlag Berlin Heidelberg New York 1982

Author

Zbigniew Semadeni lnstytut Matematyczny, Polskiej Akademii Nauk ul. Sniadeckich 8, skr. pocztowa 137,00·950 Warszawa

AMS Subject Classifications (1980): 41 A 15,46 BXX, 46B15, 46B25, 46B30, 46E15

ISBN 3-540-11481-5 Springer-Verlag Berlin Heidelberg New York ISBN 0-387-11481-5 Springer-Verlag New York Heidelberg Berlin

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to "Verwertungsgesellschaft Wort", Munich.

© by Springer-Verlag Berlin Heidelberg 1982 Printed in Germany Printing and binding: Beltz Offsetdruck, Hemsbach/Bergstr. 2141/3140-543210

Preface Writing these lecture notes I had several goals in mind: 1)

To present (in Chapters 1 and 4)

Schauder bases in spaces

C(X) and

theoretical aspects of

Co(X),

in the spirit of the iso-

metric theory of Banach spaces, including a construction of a basis in a generic separable space

Co(X).

2) To show (in Chapter 2) constructions of some classical bases of functions of a single variable. This includes the Faber­Schauder system in

C(I),

where

r = [0,1],

and the Haar system as a basis in

the Franklin system in

C(I),

C(2 w) .

3) To give an introduction to the work of Z.Ciesielski, S.Schoenefeld and others on spline bases in various spaces of differentiable functions and to the work of

on bases in certain Banach

spaces of analytic functions (Section 3.9). 4) To present (in Section 4.8) results concerning nonexistence of

Schauder

bases

with

some

special properties; typical here is

the celebrated theorem of A.M.Olevskii that no uniformly bounded orthonormal system can be a basis

in

C(I).

5) To show (in Chapter 3) constructions of bases in spaces where

1 < d < co.

C(I

d)

For two (or perhaps even four) decades it has been

known how to construct such bases, consisting of certain spline functions; in these notes we consider bases of splines of degree 1, d that is, of functions continuous on r and affine on each simplex of some triangulation of

rd.

In spite of the regularity of the construc-

tion of these bases and their nice properties, they have not yet attracted people working in numerical methods. An

reason is

that not only these functions are not differentiable, but also the rate of convergence is worse than with higher­order splines. Yet, another reason may be that in the existing literature the descriptions of the basis functions of several variables are geometrical, outlined only, without explicit formulas for the functions. This is why the d) presentation of bases in C(I is so detailed here. Also, though arra.nging the basis functions into a single sequence is