Search results for "matematica"

Il problema degli n-corpi in relatività generale

2019

Questa riproposizione in italiano dell’ultimo lavoro di Tullio Levi-Civita (1873- 1941) nasce da una esigenza culturale forte. Nel 2018 Padova e la sua Università hanno celebrato il loro grande scienziato con un importante convegno, accompagnato dalla ristampa di una selezione di suoi lavori, comprendente la sua tesi di laurea autografa. L’ultimo suo lavoro scientifico, “Le problème des n corps en relativité générale”, fu redatto in francese, e per le note vicende risalenti all’abominia fascista delle leggi razziali, fu stampato solo postumo, nel 1950, a cura dell’Accademia delle Scienze di Parigi.

MR2306791

2008

MR2306791

Operators in Rigged Hilbert Spaces, Gel’fand Bases and Generalized Eigenvalues

2022

Given a self-adjoint operator A in a Hilbert space H, we analyze its spectral behavior when it is expressed in terms of generalized eigenvectors. Using the formalism of Gel’fand distribution bases, we explore the conditions for the generalized eigenspaces to be one-dimensional, i.e., for A to have a simple spectrum.

Giovanni Novi (1826-1866). La corrispondenza con Enrico Betti ed il suo contributo matematico

2012

Some fixed point theorems for occasionally weakly compatible mappings in probabilistic semi-metric spaces

2009

We prove some common fixed point theorems in probabilistic semi-metric spaces for occasionally weakly compatible mappings satisfying a generalized contractive condition. We give also results of common fixed point for mappings satisfying a condition of integral type.

Análisis de los antecedentes histórico-filosóficos de la "paradoja cognitiva de Duval"

2015

In a famous article published in 1993, Raymond Duval highlighted a simple fact: the student may confuse the mathematical object O he is trying to build cognitively with one of its semiotic representations R(O). Duval explained that this confusion was due to a sort of inevitable paradox: only someone who has already built O, can recognize R(O) as a representation of O and not as an object in itself. Thereafter, this thought has been extremely influential for researchers. However, even if in different terms, many scholars of semiotics have emphasized the same phenomenon. In this paper we propose to remind some of them. En un famoso artículo publicado en 1993, Raymond Duval evidenciaba el sigu…

Lebesgue-type decomposition for sesquilinear forms via differences

2022

Definitions of regularity and singularity are proposed for sesquilinear forms with respect to a non-negative one and a correspondent Lebesgue-type decomposition is proved. In contrast to other Lebesgue-type decompositions established in the literature for sesquilinear forms with generic sign, the underlying idea in this paper is to write symmetric forms as the difference of non-negative sesquilinear forms.

EXISTENCE RESULTS FOR SINGULAR CONVECTIVE ELLIPTIC PROBLEMS

2021

Singular (p, q)-equations with superlinear reaction and concave boundary condition

2020

We consider a parametric nonlinear elliptic problem driven by the sum of a p-Laplacian and of a q-Laplacian (a (Formula presented.) -equation) with a singular and (Formula presented.) -superlinear reaction and a Robin boundary condition with (Formula presented.) -sublinear boundary term (Formula presented.). So, the problem has the combined effects of singular, concave and convex terms. We look for positive solutions and prove a bifurcation-type theorem describing the changes in the set of positive solutions as the parameter varies.

Some recent results on singular $ p $-Laplacian systems

2022

Some recent existence, multiplicity, and uniqueness results for singular p-Laplacian systems either in bounded domains or in the whole space are presented, with a special attention to the case of convective reactions. A extensive bibliography is also provided.