Research output: Contribution to journal › Article › peer-review
Around Efimov’s differential test for homeomorphism. / Alexandrov, Victor.
In: Beitrage zur Algebra und Geometrie, Vol. 62, No. 1, 03.2021, p. 7-20.Research output: Contribution to journal › Article › peer-review
}
TY - JOUR
T1 - Around Efimov’s differential test for homeomorphism
AU - Alexandrov, Victor
N1 - Publisher Copyright: © 2020, The Managing Editors. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/3
Y1 - 2021/3
N2 - In 1968, Efimov proved the following remarkable theorem: Letf: R2→ R2∈ C1be such thatdet f′(x) < 0 for allx∈ R2and let there exist a function a(x) > 0 and constantsC1⩾ 0 , C2⩾ 0 such that the inequalities| 1 / a(x) - 1 / a(y) | ⩽ C1| x- y| + C2and| det f′(x) | ⩾ a(x) | curl f(x) | + a2(x) hold true for allx, y∈ R2. Thenf(R2) is a convex domain andf mapsR2ontof(R2) homeomorphically. Here curl f(x) stands for the curl of f at x∈ R2. This article is an overview of analogues of this theorem, its generalizations and applications in the theory of surfaces, theory of global inverse functions, as well as in the study of the Jacobian Conjecture and the global asymptotic stability of dynamical systems.
AB - In 1968, Efimov proved the following remarkable theorem: Letf: R2→ R2∈ C1be such thatdet f′(x) < 0 for allx∈ R2and let there exist a function a(x) > 0 and constantsC1⩾ 0 , C2⩾ 0 such that the inequalities| 1 / a(x) - 1 / a(y) | ⩽ C1| x- y| + C2and| det f′(x) | ⩾ a(x) | curl f(x) | + a2(x) hold true for allx, y∈ R2. Thenf(R2) is a convex domain andf mapsR2ontof(R2) homeomorphically. Here curl f(x) stands for the curl of f at x∈ R2. This article is an overview of analogues of this theorem, its generalizations and applications in the theory of surfaces, theory of global inverse functions, as well as in the study of the Jacobian Conjecture and the global asymptotic stability of dynamical systems.
KW - diffeomorphism
KW - Efimov’s theorem
KW - Euclidean 3-space
KW - Gauss curvature
KW - Global asymptotic stability of a dynamical system
KW - Immersed surface
KW - Jacobian conjecture
KW - Milnor’s conjecture
KW - Riemannian metric
KW - Efimov's theorem
KW - THEOREM
KW - INJECTIVITY
KW - VECTOR-FIELDS
KW - GLOBAL ASYMPTOTIC STABILITY
KW - UMBILICAL POINTS
KW - MAPS
KW - Milnor's conjecture
KW - EXTRINSIC CURVATURE
KW - INITIAL DATA
KW - COMPLETE-SURFACES
UR - http://www.scopus.com/inward/record.url?scp=85096397474&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/ffd28beb-ac26-3743-8d00-62cf2c870329/
U2 - 10.1007/s13366-020-00534-3
DO - 10.1007/s13366-020-00534-3
M3 - Article
AN - SCOPUS:85096397474
VL - 62
SP - 7
EP - 20
JO - Beitrage zur Algebra und Geometrie
JF - Beitrage zur Algebra und Geometrie
SN - 0138-4821
IS - 1
ER -
ID: 26205997