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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2025 Volume 216, Number 1, Pages 3–29 (Mi sm10060)

This article is cited in 2 papers

Solvability of nonlinear degenerate equations and estimates for inverse functions

A. V. Arutyunov, S. E. Zhukovskiy

V. A. Trapeznikov Institute of Control Sciences of Russian Academy of Sciences, Moscow, Russia

Abstract: For a continuous map $F$ from a finite-dimensional real space to another such space the question of the solvability of the nonlinear equation of the form $F(x)=y$ is investigated for $y$ close to a fixed value $F(\overline x)$. To do this, the concept of $\lambda$-truncation of the map $F$ in a neighbourhood of the point $\overline x$ is introduced and examined. A theorem on the uniqueness of a $\lambda$-truncation is proved. The regularity condition is introduced for $\lambda$-truncations; it is shown to be sufficient for the solvability of the equation in question. A priori estimates for the solution are obtained.
Bibliography: 16 titles.

Keywords: nonlinear equation with parameter, abnormal point, $\lambda$-truncation, directional regularity.

MSC: 26B10

Received: 07.01.2024 and 14.10.2024

DOI: 10.4213/sm10060


 English version:
Sbornik: Mathematics, 2025, 216:1, 1–24

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© Steklov Math. Inst. of RAS, 2026