Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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Decompositions and the fixed point property for multifunctions
Get PDFRelations between the fixed point properties for some classes of multifunctions of a compact Hausdorff space X, of a decomposition space X/D, where D is an upper semi-continuous decomposition of X, and of the members of D are studied. Results are applied to some special decompositions of metric continua
Some ideals of operators between spaces of operators
Get PDFFor A ∈ L(X, Y ), B ∈ L(Z , T ) we consider the operator h : L(Y, Z ) →L(X, T ), h(U ) = BU A.We prove that in some hypotheses about A and B the operator h is in some ideal of operators. As a consequence we obtain that the ideals of Dunford-Pettis dual operator and weak∗ -norm sequentially continuous operators are projective tensor stable, Nc^dual ⊗_π D P^dual ⊂ Nc^dual , G P^dual ⊗_π D P^dual ⊂ G P^dual
Remarks on Q-oscillators representation of Hopf-type boson algebras
Get PDFWe present a method of constructing known deformed or undeformed oscillators as quotients of certain models of Hopf-type oscillator algebras, using similar techniques to those of determining fix point sets of the adjoint action of a Hopf algebra. Moreover we give a characterization of these models in terms of these quotients coupled to Euclidean Clifford algebra. A theorem is proved which provides representations of the models, induced from those of a certain type of quotient algebra
On Szasz-Mirakyan operators of functions of two variables
Get PDFWe consider Szasz-Mirakyan operators in polynomial and exponential weighted spaces of functions of two variables. We give Voronowskaya type theorem and theorem on convergence of certain sequences
Strutture pseudo-euclidee su campi di Galois
Get PDFIn this paper we define an inner product in an affine plane AG(2, q). The odd case, in a canonical rapresentation, is connected with a geometry studied by Tallini. The even case is very new since, the inner product cannot be commutative and we have an ordered perpendicularity. Finally we applied theese questions to construct a criptographic authentication system
Theory of multiindex multivariable Bessel functions and Hermite polynomials
Get PDFWe discuss the theory of multivariable multiindex Bessel functions (B.F.) and Hermite polynomials (H.P.) using the generating function method. We derive addition and multiplication theorems and discuss how generalized H.P. can be exploited as a useful complement to the theory of B.F.. We also discuss the importance of the Poisson-Charlier polynomials in the context of multiindex special functions
Investigation on stability of electrohydrodynamic shock waves
Get PDFWell-posedness of a linear mixed problem on stability of electrohydrodynamic shock waves is investigated in the paper. Stability of shock waves for a hydrodynamic model of movement of a continuum with a volume electric charge is proved
A note on line graphs
Get PDFThe aim of this note is to give several sufficient conditions, for some classes of line graphs, to be Hamiltonian
Miscellaneous identities of generalized Hermite polynomials
Get PDFWe extend a number of identities valid for the ordinary case to generalized Hermite polynomials with two indices and two variables. These identities, new to the authors knowledge, are obtained by using an operatorial procedure based on the properties of the Weyl group
Semilinear equations with strongly monotone nonlinearity
Get PDFIt is presented a method to solve semilinear equations in real Hilbert spaces. Some applications to differential equations are given