On the Kurepa and inhomogeneous Cauchy functional equations

Fuente: arXiv
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Main Authors: Aliev, Rashid, Ismailov, Vugar
Format: Preprint
Published: 2025
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author Aliev, Rashid
Ismailov, Vugar
author_facet Aliev, Rashid
Ismailov, Vugar
contents It follows from de Bruijn's results that if a continuous or $k$-th order continuously differentiable function $F(x,y)$ is a solution of the Kurepa functional equation, then it can be expressed as $F(x,y)=f(x+y)-f(x)-f(y)$ with the continuous $f$ or the $k$-th order continuously differentiable $f$, respectively. These two facts strengthen the corresponding results of Kurepa and Erdös. In this paper, we provide new and constructive proofs for these facts. In addition to practically useful recipes given here for construction of $f$, we also estimate its modulus of continuity.
format Preprint
id arxiv_https___arxiv_org_abs_2501_08949
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Kurepa and inhomogeneous Cauchy functional equations
Aliev, Rashid
Ismailov, Vugar
Classical Analysis and ODEs
It follows from de Bruijn's results that if a continuous or $k$-th order continuously differentiable function $F(x,y)$ is a solution of the Kurepa functional equation, then it can be expressed as $F(x,y)=f(x+y)-f(x)-f(y)$ with the continuous $f$ or the $k$-th order continuously differentiable $f$, respectively. These two facts strengthen the corresponding results of Kurepa and Erdös. In this paper, we provide new and constructive proofs for these facts. In addition to practically useful recipes given here for construction of $f$, we also estimate its modulus of continuity.
title On the Kurepa and inhomogeneous Cauchy functional equations
topic Classical Analysis and ODEs
url https://arxiv.org/abs/2501.08949