Continuous functions with impermeable graphs

Research output: Contribution to journalArticleResearchpeer-review

Authors

External Organisational units

  • Eötvös University Budapest
  • Institut für Mathematik und Wissenschaftliches Rechnen, Karl-Franzens-Universität Graz
  • Universität Rostock

Abstract

We construct a Hölder continuous function on the unit interval which coincides in uncountably (in fact continuum) many points with every function of total variation smaller than 1 passing through the origin. We conclude that this function has impermeable graph—one of the key concepts introduced in this paper—and we present further examples of functions both with permeable and impermeable graphs. Moreover, we show that typical (in the sense of Baire category) continuous functions have permeable graphs. The first example function is subsequently used to construct an example of a continuous function on the plane which is intrinsically Lipschitz continuous on the complement of the graph of a Hölder continuous function with impermeable graph, but which is not Lipschitz continuous on the plane. As another main result, we construct a continuous function on the unit interval which coincides in a set of Hausdorff dimension 1 with every function of total variation smaller than 1 which passes through the origin.

Details

Original languageEnglish
Pages (from-to)4778-4805
Number of pages28
JournalMathematische Nachrichten
Volume296.2023
Issue number10
Early online date7 Jun 2023
DOIs
Publication statusPublished - Oct 2023