Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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Homotopies using conformal transformation with invariant total normal twist
Get PDFThe aim of this paper is to detect a homotopy to a spherical curve with invariant total normal twist 0. Also, we use conformal transformation to prove a theorem that for any immersed closed C^3 -curve c in the Euclidean 3-space E^3 with vanishing total normal twist, there exists a Frenet curve ĉ homotopic to c in an arbitrary neighborhood of c such that the total normal twist is invariant along the homotopy between c and ĉ in that neighborhood
An infinite plate with a curvilinear hole in S-plane
Get PDFCauchy integral method has been applied to derive exact and closed expressions for Goursat\u27s functions for the first and second fundamental problems for the infinite plate weakened by a hole having arbitrary shape.The plate considered are conformally mapped on the area of the right half-plane. The work of many previous authors are considered as special cases of this work and the interesting cases when the the shape of the hole is an ellipse, a crescent, a triangle, or a cut having the shape of a circular are include as special cases
Singular bielliptic curves and Weierstrass points
Get PDFHere we study the Weierstrass points of singular bielliptic curves in characteristic 0. Most of our results are existence results of the type "there exists a bielliptic curve Y with certain singular points and with a weierstrass point P ∈ Y_{reg} with a prescribed gap sequence". Another main result is a smoothness one for the set of all genus g bielliptic curves with prescribed singularities
Wardrop equilibria in an infinite network
Get PDFIn a finite network, there is a classical theory of traffic flow, which gives existence of a Wardrop equilibrium for given OD demands and affine route costs. In this note, the existence theory is extended to infinite networks
Ample vector bundles and intrinsic quadric fibrations over irrational curves
Get PDFLet E be an ample vector bundle of rank r ≥ 2 on a smooth complex projective variety X. This work is part of the following problem: to study and classify the pair (X, E) assuming the existence of a regular section s ∈Γ (X, E) whose zero locus is a special subvariety of X . In [2] and [11], the case of Z quadric fibration, respectively of diimension 2 or more, over a smooth curve is discussed under the further hypothesis that the quadric fibration structure is induced on Z by an ample line bundle L on X . Herethe same situation is considered, and classification is given assuming the base curve to be irrational, in the more general case that the quadric fibration structure of Z is intrinsic, i.e. not a priori induced by a polarization of X
New solutions of the generalized ellipsoidal wave equation
Get PDFCertain aspects and a contribution to the theory of new forms of solutions of an algebraic form of the generalized ellipsoidal wave equation are deduced by considering the Laplace transform of a soluble system of linear differential equations. An ensuing system of non-linear algebraic equations is shown to be consistent and is numerically implemented by means of the computer algebra package MAPLE V. The main results are presented as series of hypergeometric type of there and four variables which readily lend themselves to numerical handling although this does not indicate all of the detailedanalytic properties of the solutions under consideration
On the eigenvalues of a kernel considered by A. M. Ostrowski
Get PDFBy using the inverse iteration method we improve approximation of the eigenvalues of a kernel connected with a problem considered by A.M. Ostrowski
Algorithms for the extension of precise and imprecise conditional probability assessments: an implementation with maple V
Get PDFIn this paper, we illustrate an implementation with Maple V of some procedures which allow to exactly propagate precise and imprecise probability assessments. The extension of imprecise assessments is based on a suitable generalization of the concept of coherence of de Finetti. The procedures described are supported by some examples and relevant cases
On exponential stability of C_0-quasisemigroups in Banach spaces
Get PDFInthis paper we study some stability concepts for linear systems the evolution which can be described by a C_0 -quasisemigroup.The results obtained may be regarded as generalizations of well known results of Datko, Pazy, Littman and Neerven about exponential stability of C_0 -semigroups
Semiconcavity of the value function for an exit time problem with degenerate cost
No full textA simple exit time problem with degenerate cos is here considered. Using a new technique for constructing admissible trajectories, a semiconcavity result for the value function ν is obtained. Such a property of ν is then applied to obtain optimality conditions