Showing papers in "Annali Dell'universita' Di Ferrara in 1987"

Représentation intégrale de fonctionnelles convexes sur un espace de mesures

Abstract: Partant d’un resultat abstrait de representation integrale pour une fonctionnelle convexe faiblement s.c.i. sur [Mb(Ω)]d (obtenu grâce a [1]); on etablit un resultat de convergence pour une suite de fonctionnelles du type\(F_n :\lambda \in \left[ {\mathcal{M}_b \left( \Omega \right)} \right]^d \to \left\{ {\begin{array}{*{20}c} {\int\limits_\Omega {f_n \left( { \cdot ,\frac{{d\lambda }}{{d\mu _n }}} \right)} } \\ { + \infty } \\ \end{array} d\mu _n } \right.\begin{array}{*{20}c} {si \lambda \ll \mu _n } \\ {sinon} \\ \end{array} \) μneMb+(Ω),fn: Ω×Rd→−∞, +∞] inte

On a class of 3-dimensional polyhedra

Abstract: In this paper we introduce and study a class of 3-dimensional polyhedra generalizing that ofPL manifolds with boundary.

Quelques remarques sur les courbes arithmétiquement Buchsbaum de l’espace projectif

Abstract: On donne (cf §2) un theoreme d’annulation pour la cohomologie des courbes gauches arithmetiquement Buchsbaum (aB) On developpe ensuite quelques consequences de ce theoreme Notamment on donne une description detaillee des courbes aB sous-canoniques (resp quasi-intersections completes) et de leurs proprietes (cf § 3, 4) D’autres consequences osnt mentionnees au § 5 Par ex Prop 55 resount une conjecture de Migliore sur les courbes aB de rang maximum

Relaxation of functionals with constraints on the divergence

Abstract: RiassuntoSi dà una caratterizzazione del rilassato di un funzionale integrale del tipo $$\\int\\limits_\\Omega f \\left( {x, u, Du} \\right)dx$$ con il vincolo divu=g (Ω aperto Lipschiziano,u una funzione in uno spazio di SobolevH1,p(Ω)—eventualmente con dato fissato al bordo—,f una funzione che verifica opportune condizioni di crescenza e di continuità,g∈Lp (Ω)). Si prova che il funzionale rilassato può essere rappresentato nella forma $$\\int\\limits_\\Omega \\psi \\left( {x, u, Du} \\right)dx$$ con lo stesso vincolo e si dà una formula esplicita per φ.SummarySee the Introduction.

A relaxed control problem for two-phase conductors

Abstract: An integral functional is defined on the class of the matrices, coefficients of elliptic operators, for which only two isotropic values are admissible. Its relaxation with respect toG-convergence topology is explicity computed.

Fundamental groups of branched covering spaces ofS 3

Abstract: Given a knotK⊂S 3, it is known a standard method for constructing a 4-coloured graph representing the closed orientable 3-manifoldM=M(K, d, ω) which is thed-fold covering space ofS 3 branched overK and associated to the transitived-representation ω of the knot group.

Curve aritmeticamente Buchsbaum su superfici di grado 3 e 4 dello spazio proiettivo

Abstract: Si studiano curve aritmeticamente Buchsbaum nello spazio proiettivoP3, tali che l’ordine minimo di una superficie che le contiene e 3 o 4. Per tali curve si determinano l’ordine, il genere aritmetico, il carattere numerico connesso, il modulo di Hartshorne-Rao e la curva legata di ordine minimo. Nel caso di curve situate su superfici cubiche lisce si determinano anche i multigradi corrispondenti.

Esistenza, unicità e propagazione della regolarità della soluzione del problema di Cauchy per certi operatori strettamente iperbolici con coefficienti lipschitziani rispetto al tempo

Abstract: Si studia il problema di Cauchy per operatori differenziali lineari del secondoordine strettamente iperbolici con coefficienti lipschitziani rispetto al tempo. Si trovano risultati di buona positura del problema negli spazi $$H_\infty = \mathop \cup \limits_8 H_8 , H_{ - \infty } = \mathop \cap \limits_8 H_8 , H_8 $$ gli ordinari spazi di Sobolev, e risultati di propagazione della regolaritaC ∞ della soluzione.

Sull’equilibrio di una massa fluida in rotazione

Abstract: In questa nota si studia il funzionale (11) dimostrando l’esistenza di minimi «locali» in una opportuna classe di insiemi soggetti ad un vincolo di volume, almeno nel caso in cui Ω e abbastanza «piccolo» Le tecniche usate per ottenere i risultati di esistenza portano implicitamente alla regolarita degli insiemi minimizzanti

Subbundles of maximal degree of the normal bundle of algebraic space curves almost complete intersection of special type

Abstract: LetX⊂P 3 be an irreducible smooth curve which is not a complete intersection. The main result of this paper shows that whenX is an a.c.i. of special type, i.e. its homogeneous ideal is generated by three polynomial of the same degreem, and additionallym>2, the subbundles of maximal degree of the normal bundle ofX inP 3 correspond to the singular points of maximal multiplicity of a plane curve which is the image ofX by a map\(X\mathop \to \limits^\varphi P^2 \) (the linear system of the surfaces of minimal degree throughX). In particular this normal bundle is stable. The initial case of this family of curves, i.e. form=3, has been studied by E. Ballico-Ph. Ellia with different methods.

Projective contractions along weighted projective spaces

Abstract: LetX be a normal projective variety over a fixed algebraically closed fieldK andX′⊂X an effective Cartier divisor such that (a) (X’,O X’)≅(P(Q,O P Q) whereP(Q) is the weighted projective space overK, of weightsQ=(q 1,…,q r ),r≥1; (b) N X′,X is ample, whereN=O X (−X’)/O X (−2X’) is the conormal sheaf ofX′ inX.

A note on the postulation of maximal rank curves

Abstract: Lets be the lowest degree of a surface containing a maximal rank curveY We want to compare the dimension of the space of the surfaces of degrees containingY with the dimension of the space of the surfaces of degrees+1 We apply the bound that we find for getting a bound for the third Chern class of a rank-two reflexive sheaf onPk3 with seminatural cohomology, thus answering to a conjecture proposed byR Hartshorne

On the product of two tolerances

Abstract: In the present note we study the product (composition) of two tolerances; some known results concerning the product of two equivalence relations are generalized to that of two tolerances and new results are obtained via an analysis of possible interactions among them.