Thèse de Doctorat
DOI
https://doi.org/10.11606/T.55.2020.tde-07012020-090607
Document
Auteur
Nom complet
Alex Pereira da Silva
Unité de l'USP
Domain de Connaissance
Date de Soutenance
Editeur
São Carlos, 2019
Directeur
Jury
Silva, Paulo Leandro Dattori da (Président)
Barostichi, Rafael Fernando
Bonotto, Everaldo de Mello
Rubio, Pedro Marin
Titre en anglais
Resolubility of linear Cauchy problems on Fréchet spaces and a de- layed Kaldors model
Mots-clés en anglais
Delay differential equations
Fréchet spaces
Kaldors model.
Linear Cauchy problems
Pseudodifferential operators
Resumé en anglais
The long-run aim of this thesis is to solve delay differential equations with infinite delay of the type
$\frac{d}{\mathrm{dt}}$u(t) = Au(t) + ∫t-∞ u(s)k(t - s)ds+ f (t, u(t)),

on Fréchet spaces under an extended theory of groups of linear operators; where A is a linear operator, k(s) ≥ 0 satisfies ∫0 k(s)ds = 1 and f is a nonlinear map. In order to pursue such a goal we study a discrete delay model which explains the natural economic fluctuations considering how economic stability is affected by the role of the fiscal and monetary policies and a possible government inefficiency concerning its fiscal policy decision-making. On the other hand, we start to develop such an extended theory by considering linear Cauchy problems associated to a continuous linear operator on Fréchet spaces, for which we establish necessary and sufficient conditions for generation of a uniformly continuous group which provides the unique solution. Further consequences arises by considering pseudodifferential operators with constant coefficients defined on a particular Fréchet space of distributions, namely FL2loc, and special attention is given to the distributional solution of the heat equation on FL2loc for all time, which extends the standard solution on Hilbert spaces for positive time.
Titre en portugais
Resolubilidade de problemas lineares de Cauchy em espaços de Fréchet e um modelo de Kaldor com retardo
Mots-clés en portugais
Equações diferenciais com retardo
Espaços de Fréchet
Modelo de Kaldor.
Problemas de Cauchy lineares
Resumé en portugais
O objetivo a longo prazo desta tese é resolver equações diferenciais da forma
$\frac{d}{\mathrm{dt}}$u(t) = Au(t) + ∫t-∞ u(s)k(t - s)ds+ f (t, u(t)),