On a weak form of uniform convergence

Jaroslav Fuka; Petr Holický

Commentationes Mathematicae Universitatis Carolinae (2005)

  • Volume: 46, Issue: 4, page 637-643
  • ISSN: 0010-2628

Abstract

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The notion of Δ -convergence of a sequence of functions is stronger than pointwise convergence and weaker than uniform convergence. It is inspired by the investigation of ill-posed problems done by A.N. Tichonov. We answer a question posed by M. Katětov around 1970 by showing that the only analytic metric spaces X for which pointwise convergence of a sequence of continuous real valued functions to a (continuous) limit function on X implies Δ -convergence are σ -compact spaces. We show that the assumption of analyticity cannot be omitted.

How to cite

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Fuka, Jaroslav, and Holický, Petr. "On a weak form of uniform convergence." Commentationes Mathematicae Universitatis Carolinae 46.4 (2005): 637-643. <http://eudml.org/doc/249560>.

@article{Fuka2005,
abstract = {The notion of $\Delta $-convergence of a sequence of functions is stronger than pointwise convergence and weaker than uniform convergence. It is inspired by the investigation of ill-posed problems done by A.N. Tichonov. We answer a question posed by M. Katětov around 1970 by showing that the only analytic metric spaces $X$ for which pointwise convergence of a sequence of continuous real valued functions to a (continuous) limit function on $X$ implies $\Delta $-convergence are $\sigma $-compact spaces. We show that the assumption of analyticity cannot be omitted.},
author = {Fuka, Jaroslav, Holický, Petr},
journal = {Commentationes Mathematicae Universitatis Carolinae},
keywords = {continuous functions on metric spaces; pointwise convergence; $\Delta $-convergence; analytic spaces; Hurewicz theorem; $K_\sigma $-spaces; continuous functions on metric spaces; pointwise convergence; -convergence; analytic space; Hurewicz theorem; -compact space},
language = {eng},
number = {4},
pages = {637-643},
publisher = {Charles University in Prague, Faculty of Mathematics and Physics},
title = {On a weak form of uniform convergence},
url = {http://eudml.org/doc/249560},
volume = {46},
year = {2005},
}

TY - JOUR
AU - Fuka, Jaroslav
AU - Holický, Petr
TI - On a weak form of uniform convergence
JO - Commentationes Mathematicae Universitatis Carolinae
PY - 2005
PB - Charles University in Prague, Faculty of Mathematics and Physics
VL - 46
IS - 4
SP - 637
EP - 643
AB - The notion of $\Delta $-convergence of a sequence of functions is stronger than pointwise convergence and weaker than uniform convergence. It is inspired by the investigation of ill-posed problems done by A.N. Tichonov. We answer a question posed by M. Katětov around 1970 by showing that the only analytic metric spaces $X$ for which pointwise convergence of a sequence of continuous real valued functions to a (continuous) limit function on $X$ implies $\Delta $-convergence are $\sigma $-compact spaces. We show that the assumption of analyticity cannot be omitted.
LA - eng
KW - continuous functions on metric spaces; pointwise convergence; $\Delta $-convergence; analytic spaces; Hurewicz theorem; $K_\sigma $-spaces; continuous functions on metric spaces; pointwise convergence; -convergence; analytic space; Hurewicz theorem; -compact space
UR - http://eudml.org/doc/249560
ER -

References

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  1. Bartoszyński T., Judah H., Shelah S., The Cichoń diagram, J. Symbolic Logic 58 (1993), 401-423. (1993) MR1233917
  2. Fuka J., On the δ -convergence, Acta Universitatis Purkynianae 42, Czech-Polish Mathematical School, Ústí nad Labem, 1999, 63-64. 
  3. Jech T., Set Theory, Second Edition, Perspectives in Mathematical Logic, Springer, Berlin, 1997. MR1492987
  4. Just W., Weese M., Discovering Modern Set Theory. II, Graduate Studies in Mathematics, Vol. 18, American Mathematical Society, Providence, 1997. Zbl0887.03036MR1474727
  5. Kechris A.S., Classical Descriptive Set Theory, Springer, New York, 1995. Zbl0819.04002MR1321597
  6. Martin D.A., Solovay R.M., Internal Cohen extensions, Ann. Math. Logic 2 (1970), 143-178. (1970) Zbl0222.02075MR0270904
  7. Solovay R.M., Tennenbaum S., Iterated Cohen extensions and Souslin's problem, Ann. of Math. 94 (1971), 201-245. (1971) Zbl0244.02023MR0294139
  8. Tichonov A.N., On the regularization of ill-posed problems (Russian), Dokl. Akad. Nauk SSSR 153 (1963), 49-52. (1963) MR0162378

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