English

A superposition theorem of Kolmogorov type for bounded continuous functions

Classical Analysis and ODEs 2021-05-06 v2

Abstract

Let C(Rn)C({\mathbb R}^n) denote the set of real valued continuous functions defined on Rn{\mathbb R}^n. We prove that for every n2n\ge 2 there are positive numbers λ1,,λn\lambda _1 , \ldots , \lambda _n and continuous functions ϕ1,,ϕmC(R)\phi_1 ,\ldots , \phi _m \in C({\mathbb R}) with the following property: for every bounded and continuous fC(Rn)f\in C( {\mathbb R}^n ) there is a continuous function gC(R)g\in C({\mathbb R} ) such that f(x)=q=1mg(p=1nλpϕq(xp))f(x)=\sum_{q=1}^m g\left( \sum_{p=1}^n \lambda _p \phi _q (x_p ) \right) for every x=(x1,,xn)Rnx=(x_1 ,\ldots , x_n )\in {\mathbb R}^n. Consequently, every fC(Rn)f\in C({\mathbb R}^n) can be obtained from continuous functions of one variable using compositions and additions.

Keywords

Cite

@article{arxiv.2104.13696,
  title  = {A superposition theorem of Kolmogorov type for bounded continuous functions},
  author = {M. Laczkovich},
  journal= {arXiv preprint arXiv:2104.13696},
  year   = {2021}
}
R2 v1 2026-06-24T01:35:44.444Z