Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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Solvability of the Dirichlet problem in W^{2,p} for elliptic equations with discontinuous coefficients in unbounded domains
Get PDFIn this paper some W^{2, p}-estimates for the solutions of the Dirichlet problem for a class of elliptic equations with discontinuous coefficients in unbounded domains are obtained. As a consequence, an existence and uniqueness theorem for such a problem is proved
Spectral analysis for a discontinuous second order elliptic operator
Get PDFThe spectrum of a second order elliptic operator S, with ellipticity constant α discontinuous in a point, is studied in L^p spaces. It turns out that, for (α, p) in a set A, classical results for the spectrum of smooth elliptic operators (see e.g. [3]) remain true for S; in particular, it is proved that S is the infinitesimal generator of an holomorphic semigroup . If (α, p) not in A, then the spectrum of S is the whole complex plane
Infinitely many solutions to the Neuman problem for quasilinear elliptic systems
Get PDF In this paper we deal with the existence of weak solutions for the Neumann problem. The existence of solutions is proved by applying a critical point theorem obtained by B. Ricceri as consequence of a more general variational principle
On generalized Kummer of rank 3 vector bundles over a genus 2 curve
Get PDFLet X be a smooth projective complex curve and let U_X (r, d) be the moduli space of semi-stable vector bundles of rank r and degree d on X (see [8])
Hilbert presso la Georg August Universität Göttingen: ieri ed oggi
No full textOggi: seguendo la circonvallazione ..
L\u27attualità di David Hilbert - tavola rotonda coordinata da V. Villani
No full textQui di seguito sono riportati gli interventi alla tavola rotonda, ..
Toeplitz matrix and product Nystrom methods for solving the singular integral equation
Get PDFThe Toeplitz matrix and the product Nystrom methods are applied to an integral equation of the second kind. We consider two cases: logarithmic kernel and Hilbert kernel. The two methods are applied to two integral equations with known exact solutions. The error in each case is calculated
Some measurability and continuity properties of arbitrary real functions
Get PDFGiven an arbitrary real function f , the set D_f of all points where f admits approximate limit is the maximal (with respect to the relation of inclusion except for a nullset) measurable subset of the real line having the properties that the restriction of f to D_f is measurable, and f is approximately continuous at almost every point of D_f . These results extend the well-known fact that a function is measurable if and only if it is approximately continuous almost everywhere. In addition, there exists a maximal G_δ -set C_f (which can be actually constructed from f ) such that it is possible to find a functiong = f almost everywhere, whose set of points of continuity is exactly C_f
Stability of Jensen\u27s equations in two normed spaces
Get PDFSome stability questions of the Jensen\u27s functional inequality in the setting of 2-normed spaces are derived in this article. Few more results are given on approximate isometries
A Liouville-type theorem for the homogeneous wave equation
Get PDFIn this paper, we characterize those bounded from below solutions of a homogeneous wave equation on R^2 which are constant