Le Matematiche  

Silvio Greco, Karlheinz Kiyek

Let a be a regular local two-dimensional ring, and let m = (x, y) be its maximal ideal. Let m > n > 1 be coprime integers, and let p be the integral closure of the ideal (x^m , y^n ). Then p is a simple complete m-primary ideal, and its value semigr... see more

Alexander Blokhin, Eugenia Mishchenko

     In the article, a modified initial-boundary value problem on stability of shock waves in a viscous gas is constructed and studied.

Paola Cristofori

We introduce a generalization of the regular genus, a combinatorial invariant of PL manifolds ([10]), which is proved to be strictly related, in dimension three, to generalized Heegaard splittings defined in [12].

Paolo Manselli, Francesco Ragnedda

The spectrum of a second order elliptic operator S, with ellipticity constant a discontinuous in a point, is studied in L^p spaces. It turns out that, for (a, p) in a set A, classical results for the spectrum of smooth elliptic operators (see e.g. [3]) re... see more

Dumitru Motreanu

The aim of this note is to point out that the basic argument in the proof of Theorem 2 in [5] does not work. Comments on this topic are given.

Bogdan Sasu

We present a new approach for the theorems of Perron type for exponential expansiveness of one-parameter semigroups in terms of l^p(N, X) spaces. We prove that an exponentially bounded semigroup is exponentially expansive if and only if the pair (l^p (N, ... see more

Antonio Giudeppe Di Falco

      In this paper we deal with the existence of weak solutions for the Neumann problem.                       &nb... see more

Roberto Argiolas

In this paper we consider a two phases variational problem related to a functional F. In particular we obtain results about the smoothness of the free boundary {u = 0}.

Tomonari Suzuki

In this short paper, we prove fixed point theorems for nonexpansive mappings whose domains are unbounded subsets of Banach spaces. These theorems are generalizations of Penot's result in [4].

Maria Flavia Mammana

Geometric transformations have been included in school programs since long now.