Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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Projectively Cohen-Macaulay surfaces of small degree in P^5
Get PDFIn this paper we consider the nondegenerate projectively Cohen-Macaulay (p.C.M.) surfaces of small degree in P^5 . We determine those of degree d ≤ 9 and all candidate rational surfaces as p.C.M. surfaces
Analytic semigroup generated by an elliptic operator with discontinuous coefficients
Get PDFWe consider the generation of analytic semigroups by elliptic operators with discontinuous coefficients
Poisson kernel for a parabolic problem
Get PDFIn this paper we obtain a representation for the solution of a parabolic mixed problem
Triangular projective planes of order q and (q+1)-arcs
Get PDFWe suitably define the triangular projective planes of order q and connect them with the (q + 1)-arcs. In particular, a finite projective plane is either triangular, or contains a lot of (q + 1)-arcs
Interpolation of Besov spaces and applications
Get PDFWe define the analytic Besov spaces on a bounded symmetric domain associated with a rearrangement invariant space, give a description in terms of certain differential operators, prove an interpolation theorem and find their dual space; finally, as an application we formulate necessary and sufficient onditions in order to little Hankel operator H_f belongs to S_E , the Schatten ideal associated with a given rearrangement invariant sequence space E
Fredholm-Volterra integral equation of the first kind with potential kernel
Get PDFA series method is used to separate the variables of position and time for the Fredholm-Volterra integral equation of the first kind and the solution of the system in L_2 [0,1] × C[0,T], 0 ≤ t ≤ T < ∞ is obtained, the Fredholm integral equation is discussed using Krein\u27s method. The kernel is written in a Legendre polynomial form. Some important relations are also, established and discussed
Fat points on a generic almost complete intersection
Get PDFWe study homogeneous schemes of fat points in P^2 whose support is either a complete intersection (CI for short) generated by two generic forms or a CI minus a point
A remark on the planar non linear elliptic oblique derivative problem
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Applicazioni (h,A)-lineari omomorfismi di M_A-ipergruppoidi
Get PDFIn the papers [9], [10] we introduced and studied M_λ -hypergroupoids; also, we obtained some results on the automorphism group of a G_ λ -hypergroupoid. In particular, given a group G and one of its element λ, we proved that the automorphisms of the corresponding G_λ -hypergroupoid are the one-one maps f : G → G which are λ-linea.A natural generalization of the notion of λ-linearity is the notion of (h, A, B)-linearity, introduced in the present paper. Theorem 1.7 provides the existence and uniqueness of a (h, A, B)-linear map. Theorem 2.3 gives the cardinality of the group Λ(G A ) of complete, bijective (h, A)-linear maps. In Theorem 2.7 we prove that Λ(G A ) is a semi-direct product.The notion of M_A -hypergroupoid is defned in the last section, via group actions on sets. We also study their homomorphisms and prove that the M_A -hypergroupoid is a hypergroup or a join-space according to the set A being a stable part or a subgroup of G
Errata corrige of "Centers of planar polynomial systems, a review"
Get PDFLe Matematiche Vol. 53, Fasc. II (1998), 207-24