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JOURNALS // Trudy Instituta Matematiki i Mekhaniki UrO RAN // Archive

Trudy Inst. Mat. i Mekh. UrO RAN, 2024 Volume 30, Number 4, Pages 224–233 (Mi timm2140)

One example of a continuous nowhere differentiable function whose modulus of continuity does not exceed a given one

A. I. Rubinshtein, D. S. Telyakovskii

Moscow Engineering Physics Institute (National Nuclear Research University)

Abstract: There exist positive numbers $C$ and $c$ such that, for an arbitrary concave up function $\omega(t)$ of the modulus of continuity type with $\omega(t)/t\to+\infty$ as $t\to+0$, one can construct an example of a continuous nowhere differentiable Weierstrass-type function $W_\omega(x)$ satisfying the following conditions: $1^{\circ}$. The modulus of continuity of $W_\omega(x)$ does not exceed $C\omega(t)$. $2^{\circ}$. For each point $x_0$, there exists a sequence $\{x_n\}$ convergent to $x_0$, such that $|W_\omega(x_n)-W_\omega(x_0)|>c\,\omega(|x_n-x_0|)$ for each $n$. $3^{\circ}$. At each point $x_0$, the derivative numbers of $W_\omega(x)$ take all values from the interval $[-\infty;+\infty]$.

Keywords: modulus of continuity, nowhere differentiable continuous function, derivative numbers, Weierstrass-type nowhere differentiable continuous function.

UDC: 517.518.153

MSC: 26A15, 26A16

Received: 07.08.2024
Revised: 07.11.2024
Accepted: 18.11.2024

DOI: 10.21538/0134-4889-2024-30-4-224-233



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