1,720,965 research outputs found
Global continuation in euclidean spaces of the perturbed unit eigenvectors corresponding to a simple eigenvalue
No full textIn the Euclidean space Rk, we consider the perturbed eigenvalue problem Lx + εN(x) = λx, ||x|| = 1, where ε, λ are real parameters, L is a linear endomorphism of Rk, and N: Sk−1 → Rk is a continuous map defined on the unit sphere of Rk . We prove a global continuation result for the solutions (x, ε, λ) of this problem. Namely, under the assumption that x_* is one of the two unit eigenvectors of L corresponding to a simple eigenvalue λ_*, we show that, in the set of all the solutions, the connected component containing (x_*, 0, λ_*) is either unbounded or meets a solution (x*, 0, λ*) having x* ≠ x_*. Our result is inspired by a paper of R. Chiappinelli concerning the local persistence property of eigenvalues and eigenvectors of a perturbed self-adjoint operator in a real Hilbert space
On the existence of forced oscillations for the spherical pendulum acted on by a retarded periodic force
No full textGlobal persistence of the unit eigenvectors of perturbed eigenvalue problems in hilbert spaces: The odd multiplicity case
No full textWe study the persistence of eigenvalues and eigenvectors of perturbed eigenvalue problems in Hilbert spaces. We assume that the unperturbed problem has a nontrivial kernel of odd dimension and we prove a Rabinowitz-type global continuation result. The approach is topological, based on a notion of degree for oriented Fredholm maps of index zero between real differentiable Banach manifolds
THE BROUWER DEGREE ASSOCIATED TO CLASSICAL EIGENVALUE PROBLEMS AND APPLICATIONS TO NONLINEAR SPECTRAL THEORY
No full textThanks to a connection between two completely different topics, the classical eigenvalue problem in a finite dimensional real vector space and the Brouwer degree for maps between oriented differentiable real manifolds, we are able to solve, at least in the finite dimensional context, a conjecture regarding global continuation in nonlinear spectral theory that we formulated in some recent papers. The infinite dimensional case seems nontrivial, and is still unsolved
Differential Topology and General Equilibrium with Complete and Incomplete Markets
No full textThe goal of this publication is to provide basic tools of differential topology to study systems of nonlinear equations and to apply them to the analysis of general equilibrium models with complete and incomplete markets. The main content of general equilibrium analysis is to study existence, (local) uniqueness and efficiency of equilibria. To study existence Differential Topology and General Equilibrium with Complete and Incomplete Markets combines two features. First order conditions (of agents’ maximization problems) and market clearing conditions, instead of aggregate excess demand function. Then, the application to that “extended system” of a homotopy argument, which is stated and proved in a relatively elementary manner. Local uniqueness and smooth dependence of the endogenous variables from the exogenous ones are studied using a version of a so-called parametric transversality theorem. In a standard general equilibrium model, all equilibria are efficient, but that is not the case if some imperfection, like incomplete markets, asymmetric information, strategic interaction, is added. Then, for almost all economies, equilibria are inefficient, and an outside institution can Pareto Improve upon the market outcome. Those results are proved showing that a well-chosen system of equations has no solutions.
The target audience of Differential Topology and General Equilibrium with Complete and Incomplete Markets consists of researchers interested in Economic Theory. The needed background is multivariate analysis, basic linear algebra and basic general topology
An infinite dimensional version of the intermediate value theorem
Full text linkLet f = I - k be a compact vector field of class C1 on a real Hilbert space H. In the spirit of Bolzano's Theorem on the existence of zeros in a bounded real interval, as well as the extensions due to Cauchy (in R2) and Kronecker (in Rk), we prove an existence result for the zeros of f in the open unit ball B of H. Similarly to the classical finite dimensional results, the existence of zeros is deduced exclusively from the restriction f|S of f to the boundary S of B. As an extension of this, but not as a consequence, we obtain as well an Intermediate Value Theorem whose statement needs the topological degree. Such a result implies the following easily comprehensible, nontrivial, generalization of the classical Intermediate Value Theorem: If a half-line with extreme q ?/ f(S) intersects transversally the function f|S for only one point of S, then any value of the connected component of H\f(S) containing q is assumed by f in B. In particular, such a component is bounded
Global continuation of periodic solutions for retarded functional differential equations on manifolds
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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