Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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On an approach to studying the stability of shock waves in a viscous gas
Get PDF In the article, a modified initial-boundary value problem on stability of shock waves in a viscous gas is constructed and studied
L\u27influenza di David Hilbert nella teoria dei numeri
No full textI contributi di Hilbert nella teoria dei numeri sono molteplici. Ci soffermeremo solo su due aspetti, che sembra abbiano influenzato in grande misura la teoria dei numeri nel ventesimo secolo: la teoria dei corpi di classe e il teorema di irriducibilità. Infine daremo brevi cenni sui problemi riguardanti la teoria dei numeri nella famosa lista dei 23 problemi di Hilbert
I "Grundlagen der Geometrie" e i libri di testo di Geometria in Italia
No full textDavid Hilbert cominciò ad interessarsi ai fondamenti della Geometria sin dal 1891, ..
On the geometry of the Coble-Dolgachev sextic
Get PDFIn this paper, we study the intersection of the Coble-Dolgachev sextic with special projective spaces. Let us recall that the Coble-Dolgachev sextic C_6 is the branch divisor of a double cover map. The adjunction of divisors is an involution of Pic^1(X) that lifts to a non-trivial involution. The fixed locus Fix(τ) is the disjoint union of two projective spaces P^4 and P^3
Symmetrization of mathematical model of charge transport in semiconductors
Get PDFA mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved
Colouring of Voloshin for ATS(v)
Get PDFA mixed hypergraph is a triple H=(S,C,D), where S is the vertex set and each of C,D is a family of not-empty subsets of S, the C-edges and D-edges respectively. A strict k-colouring of H is a surjection f from the vertex set into a set of colours {1, 2, . . . , k} so that each C-edge contains at least two distinct vertices x, y such that f(x) = f(y) and each D-edge contains at least two vertices x, y such that f(x)=f(y). For each k ∈ {1, 2, . . . , |S|}, let r_k be the number of partitions of the vertex set into k not-empty parts (the colour classes) such that the colouring constraint is satisfied on each C-edge and D-edge. The vector R(H ) = (r_1 , . . . , r_k ) is called the chromatic spectrum of H. These concepts were introduced by V. Voloshin in 1993 [6].In this paper we examine colourings of mixed hypergraphs in the case that H is an ATS(v)
Hilbert e la logica
No full textDavid Hilbert ha coltivato un profondo interesse per i fondamenti, ..
Fixed point theorems for asymptotically contractive mappings
Get PDFIn 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\u27s result in [4]
Generalized regular genus for manifolds with boundary
Get PDFWe 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]
Existence of three periodic solutions for a non-autonomous second order system
Get PDFThe purpose of the present paper is to establish a multiplicity result for some differencial system