Modules of vector fields, differential forms and degenerations of differential systems

1996 ◽  
Vol 95 (1) ◽  
pp. 411-428 ◽  
Author(s):  
P. Mormul ◽  
M. Zhitomirskii

2005 ◽  
Vol 07 (06) ◽  
pp. 747-768 ◽  
Author(s):  
XIONGPING DAI

Let 𝔛r(M), r ≥ 1, denote the space of all Cr vector fields over a compact, smooth and boundaryless Riemannian manifold M of finite dimension; let [Formula: see text], 1 ≤ ℓ ≤ dim M, be the bundle of orthonormal ℓ-frames of the tangent space TM of M. For any V ∈ 𝔛r(M), Liao defined functions [Formula: see text], k = 1, …, ℓ, on [Formula: see text], which are qualitatively equivalent to the Lyapunov exponents of the differential system V. In this paper, the author shows that every [Formula: see text] depends Cr-1-continuously upon [Formula: see text] and Cr-continuously on [Formula: see text] for any given V. In addition, applying the qualitative functions, the author generalizes Liao's global linearization along a given orbit of V and considers the stochastic stability of Lyapunov spectra of linear skew-product flows based on a given ergodic system.



Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan

This chapter presents some elements of differential geometry, the ‘vector’ version of Euclidean geometry in curvilinear coordinates. In doing so, it provides an intrinsic definition of the covariant derivative and establishes a relation between the moving frames attached to a trajectory introduced in Chapter 2 and the moving frames of Cartan associated with curvilinear coordinates. It illustrates a differential framework based on formulas drawn from Chapter 2, before discussing cotangent spaces and differential forms. The chapter then turns to the metric tensor, triads, and frame fields as well as vector fields, form fields, and tensor fields. Finally, it performs some vector calculus.





2017 ◽  
Vol 27 (02) ◽  
pp. 1750022 ◽  
Author(s):  
Maurício Firmino Silva Lima ◽  
Claudio Pessoa ◽  
Weber F. Pereira

We study a class of planar continuous piecewise linear vector fields with three zones. Using the Poincaré map and some techniques for proving the existence of limit cycles for smooth differential systems, we prove that this class admits at least two limit cycles that appear by perturbations of a period annulus. Moreover, we describe the bifurcation of the limit cycles for this class through two examples of two-parameter families of piecewise linear vector fields with three zones.





2012 ◽  
Vol 22 (06) ◽  
pp. 1250138 ◽  
Author(s):  
MAURÍCIO FIRMINO SILVA LIMA ◽  
JAUME LLIBRE

In this paper, we consider a class of planar continuous piecewise linear vector fields with three zones. Using the Poincaré map, we show that these systems admit always a unique limit cycle, which is hyperbolic.



Axioms ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 118
Author(s):  
Larry Bates ◽  
Richard Cushman ◽  
Jędrzej Śniatycki

In this paper, we study differential forms and vector fields on the orbit space of a proper action of a Lie group on a smooth manifold, defining them as multilinear maps on the generators of infinitesimal diffeomorphisms, respectively. This yields an intrinsic view of vector fields and differential forms on the orbit space.



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