On one nearly everywhere continuous and nowhere differentiable function, that defined by automaton with finite memory

TL;DR

This paper investigates a specific ternary-based function defined via automaton with finite memory, analyzing its properties including continuity, nowhere differentiability, fractal nature, and providing various representations.

Contribution

It introduces and studies a new class of functions defined by digit transformations in ternary representation, with detailed analysis of their mathematical properties.

Findings

The function is continuous everywhere and nowhere differentiable.

It exhibits fractal properties and complex local structure.

Equivalent representations and auxiliary functions are established.

Abstract

This paper is devoted to the investigation of the following function $$ f: x=\Delta^{3}_{\alpha_{1}\alpha_{2}...\alpha_{n}...}{\rightarrow} \Delta^{3}_{\varphi(\alpha_{1})\varphi(\alpha_{2})...\varphi(\alpha_{n})...}=f(x)=y, $$ where $\varphi(i)=\frac{-3i^{2}+7i}{2}$, $ i \in N^{0}_{2}=\{0,1,2\}$, and $\Delta^{3}_{\alpha_{1}\alpha_{2}...\alpha_{n}...}$ is the ternary representation of $x \in [0;1]$. That is values of this function are obtained from the ternary representation of the argument by the following change of digits: 0 by 0, 1 by 2, and 2 by 1. This function preserves the ternary digit $0$. Main mapping properties and differential, integral, fractal properties of the function are studied. Equivalent representations by additionally defined auxiliary functions of this function are proved. This paper is the paper translated from Ukrainian (the Ukrainian variant available at https://www.researchgate.net/publication/292970012). In 2012, the Ukrainian variant of this paper was represented by the author in the International Scientific Conference "Asymptotic Methods in the Theory of Differential Equations" dedicated to 80th anniversary of M. I. Shkil (the conference paper available at https://www.researchgate.net/publication/301765319). In 2013, the investigations of the present article were generalized by the author in the paper "One one class of functions with complicated local structure" (https://arxiv.org/pdf/1601.06126.pdf) and in the several conference papers (available at: https://www.researchgate.net/publication/301765326, https://www.researchgate.net/publication/303052308).