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Alfredo Lorenzi

Publications and source records attributed to Alfredo Lorenzi.

2 recordsLinked to original sources

A strongly ill-posed problem for a degenerate parabolic equation with unbounded coefficients in an unbounded domain $Ω\times {\mathcal O}$ of $\R^{M+N}$

In this paper we deal with a strongly ill-posed second-order degenerate parabolic problem in the unbounded open set $Ω\times {\mathcal O}\subset \mathbb R^{M+N}$, related to a linear equation with unbounded coefficients, with no initial condition, but endowed with the usual Dirichlet condition on $(0,T)\times \partial(Ω\times {\mathcal O})$ and an additional condition involving the $x$-normal derivative on $Γ\times {\mathcal O}$, $Γ$ being an open subset of $Ω$. The task of this paper is twofold: determining sufficient conditions on our data implying the uniqueness of the solution $u$ to the boundary value problem as well as determining a pair of metrics with respect of which $u$ depends continuously on the data. The results obtained for the parabolic problem are then applied to a similar problem for a convolution integrodifferential linear parabolic equation.

math.AP

Some identification problems for integro-differential operator equations

We consider, in a Hilbert space $H$, the convolution integro-differential equation $u''(t)-h*Au(t)=f(t)$, $0\le t\le T$, $h*v(t)=\int_0^t h(t-s)v(s) ds$, where $A$ is a linear closed densely defined (possibly selfadjoint and/or positive definite) operator in $H$. Under suitable assumptions on the data we solve the inverse problem consisting of finding the kernel $h$ from the extra data (measured data) of the type $g(t):=(u(t),ϕ)$, where $ϕ$ is some eigenvector of $A^*$. An inverse problem for the first-order equation $u'(t)-l*Au(t)=f(t)$, $0\le t\le T$, is also studied when $A$ enjoys the same properties as in the previous case.

math.FA