Displaying similar documents to “Una teoria-quadro per i fondamenti della matematica”

Una teoria-quadro per i fondamenti della matematica

Ennio De Giorgi, Marco Forti (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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We propose a "natural" axiomatic theory of the Foundations of Mathematics (Theory Q) where, in addition to the membership relation (between elements and classes), pairs, sets, natural numbers, n-tuples and operations are also introduced as primitives by means of suitable ground classes. Moreover, the theory Q allows an easy introduction of other mathematical and logical entities. The theory Q is finitely axiomatized in § 2, using a first-order language with a binary relation (membership)...

Alcune proprietà degli spazi quasi algebrici

Fulvio Lazzeri, Alberto Tognoli (1969)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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A q-algebraic function is an analytic function that is in the algebraic closure of the ring of polynomials. In this work we study the q-algebraic spaces (i.e. the ringed spaces that locally are isomorphic to the locus of zeros of a finite number of q-algebraic functions) and we prove, for instance, that any q-algebraic, compact, connected manifold of 𝐑 n is homogeneous (in the q-algebraic sense).

Sintesi di RNA in embrioni di Xenopus trattati con LiCl

Marisa Leonardi Cigada, Fiorenza Laria De Bernardi, Anna Maria Bolzern (1972)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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We studied RNA synthesis in Xenopus laevis embryos at the gastrula stage, using both 001 M LiCl concentration, which causes malformations, and lower concentrations to 0.0025 M that allow normal development. A preliminary series of observations on CO 2 14 incorporation in treated Xenopus embryos revealed that LiCl concentrations below 0.01 M increase the labelled RNA to 38%. On the contrary, in embryos treated with LiCl concentrations above 0.01 M there is a lower incorporation than in the...

Un'osservazione sulle classi di Fitting normali

Guido Zappa (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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We prove that a Fitting class of finite soluble groups is normal if and only if it verifies the condition α ) (see n. 2). Unlike the definition of normal Fitting class, this condition is “constructive”.

Un'osservazione sulle classi di Fitting normali

Guido Zappa (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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We prove that a Fitting class of finite soluble groups is normal if and only if it verifies the condition α ) (see n. 2). Unlike the definition of normal Fitting class, this condition is “constructive”.

Sul collasso di un ammasso di materia disgregata. Nota II

Dionigi Galletto (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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With reference to Nota I, the hypothesis that the cluster 𝒰 is spherical is substituted by the hypothesis that it has an isotropic behaviour with respect to a given frame of reference O with origin in an element O internal to 𝒰 . The kinematical behaviour of 𝒰 during the collapse with respect to the frames of reference with origin in the elements of 𝒰 and in translatory motion with respect to O is studied. This behaviour is the same with respect to each of such frames, which are in translatory...

Sul collasso di un ammasso di materia disgregata. Nota II

Dionigi Galletto (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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With reference to Nota I, the hypothesis that the cluster 𝒰 is spherical is substituted by the hypothesis that it has an isotropic behaviour with respect to a given frame of reference O with origin in an element O internal to 𝒰 . The kinematical behaviour of 𝒰 during the collapse with respect to the frames of reference with origin in the elements of 𝒰 and in translatory motion with respect to O is studied. This behaviour is the same with respect to each of such frames, which are in translatory...

Su possibili stati termici della crosta granitica

Luigi Forni (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Possible thermal states of the granite crust. Apart from transient thermal regiments, the thermal state of the granite crust is solely determined by the flow from the upper mantle and the distribution of radiogenic sources (Birch et alii, 1968). In wiew of this premiss, a study was made of four actual thermal situations to determine both the development of radiogenic heat and that ascribable to the flow from the upper mantle. It was found that: a) the temperature increases caused by...

Su possibili stati termici della crosta granitica

Luigi Forni (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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Possible thermal states of the granite crust. Apart from transient thermal regiments, the thermal state of the granite crust is solely determined by the flow from the upper mantle and the distribution of radiogenic sources (Birch et alii, 1968). In wiew of this premiss, a study was made of four actual thermal situations to determine both the development of radiogenic heat and that ascribable to the flow from the upper mantle. It was found that: a) the temperature increases caused by...

Ricerca di conformazioni di minima energia potenziale intramolecolare mediante un nuovo metodo di minimizzazione globale.

Camillo Tosi, Raffaella Pavani, Roberto Fusco, Filippo Aluffi-Pentini, Valerio Parisi, Francesco Zirilli (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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A recent method for the global optimization of a real valued function defined in the n -dimensional euclidean space has been applied to the detection of the most stable conformation of a molecule. The method, inspired by the quantum mechanical theory of diffusion across potential barriers, finds the deepest minimum of the intramolecular energy hypersurface by following the asymptotic behaviour of the paths of a system of stochastic differential equations. As an example of its application,...

Ricerca di conformazioni di minima energia potenziale intramolecolare mediante un nuovo metodo di minimizzazione globale.

Camillo Tosi, Raffaella Pavani, Roberto Fusco, Filippo Aluffi-Pentini, Valerio Parisi, Francesco Zirilli (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

A recent method for the global optimization of a real valued function defined in the n -dimensional euclidean space has been applied to the detection of the most stable conformation of a molecule. The method, inspired by the quantum mechanical theory of diffusion across potential barriers, finds the deepest minimum of the intramolecular energy hypersurface by following the asymptotic behaviour of the paths of a system of stochastic differential equations. As an example of its application,...

Le equazioni di Eulero dal punto di vista delle inclusioni differenziali

Camillo De Lellis (2008)

Bollettino dell'Unione Matematica Italiana

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In a recent joint paper with L. Székelyhidi we have proposed a new point of view on weak solutions of the Euler equations, describing the motion of an ideal incompressible fluid in n with n 2 . We give a reformulation of the Euler equations as a differential inclusion, and in this way we obtain transparent proofs of several celebrated results of V. Scheffer and A. Shnirelman concerning the non-uniqueness of weak solutions and the existence of energy-decreasing solutions. Our results are...

Sottospazi invarianti per operatori lineari T-invarianti rispetto ad un gruppo di omeomorfismi

Lucilla Bassotti Rizza (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Theory of T -invariant linear operators which was considered for a group of congruences [2], [3] is now extended to a group of homeomorphisms. An analysis is carried out in order to establish to what extent the main results of the previous theory still hold under the actual very general assumptions.

Sulle singolarità delle soluzioni di un problema di Dirichlet per un'equazione iperbolica del secondo ordine

Bruno Firmani (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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A solution u of a particular Dirichlet problem for a non-linear 2nd order hyperbolic equation is regular at any point of the boundary but one point. The kind of singularity which u exhibits at this point is investigated.

Sottospazi invarianti per operatori lineari T-invarianti rispetto ad un gruppo di omeomorfismi

Lucilla Bassotti Rizza (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

Theory of T -invariant linear operators which was considered for a group of congruences [2], [3] is now extended to a group of homeomorphisms. An analysis is carried out in order to establish to what extent the main results of the previous theory still hold under the actual very general assumptions.

Sul problema dell'autoriferimento

Ennio De Giorgi, Marco Forti, Vincenzo M. Tortorelli (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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We formulate, within the frame-theory Q for the foundations of Mathematics outlined in [2], a list L of axioms which state that almost all "interesting" collections and almost all "interesting" operations are elements of the universe. The resulting theory Q + L would thus have the important foundational feature of being completely self-contained. Unfortunately, the whole list L is inconsistent, and we are led to formulate the following problem, which we call the problem of self-reference:...

Sul problema dell'autoriferimento

Ennio De Giorgi, Marco Forti, Vincenzo M. Tortorelli (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

We formulate, within the frame-theory Q for the foundations of Mathematics outlined in [2], a list L of axioms which state that almost all "interesting" collections and almost all "interesting" operations are elements of the universe. The resulting theory Q + L would thus have the important foundational feature of being completely self-contained. Unfortunately, the whole list L is inconsistent, and we are led to formulate the following problem, which we call the problem of self-reference:...

Seminorme submoltiplicative su algebre di funzioni

Nicola Rodino (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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In this note we study algebra seminorms on a functions algebra and we relate the existence of algebra norms on C ( X ) with the topology of X . Also a theorem, that states which are the continuous characters, is demonstrated in a class of seminormed algebras.

Seminorme submoltiplicative su algebre di funzioni

Nicola Rodino (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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In this note we study algebra seminorms on a functions algebra and we relate the existence of algebra norms on C ( X ) with the topology of X . Also a theorem, that states which are the continuous characters, is demonstrated in a class of seminormed algebras.

Funzioni ( p , q ) -convesse

Ennio De Giorgi, Antonio Marino, Mario Tosques (1982)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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We study a class of functions which differ essentially from those which are the sum of a convex function and a regular one and which have interesting properties related to Γ -convergence and to problems with non-convex constraints. In particular some results are given for the associated evolution equations.

Su una nuova classe di spazi affini generalizzati di Sperner

Giorgio Nicoletti (1975)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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In this paper a new class of Sperner’s affine generalized spaces is constructed from desarguesian affine spaces of dimension 3 and order q 2 ( q prime odd > 3 power); these spaces have the property of containing q 3 + q 2 + q Hughes planes. The procedure I have used can easily be applied to a similar affine desarguesian space of any (finite) dimension; in case of dimension 2 we find the (regular) Hughes plane of order q 2 .

Su una classe di gruppi finiti supersolubili

Alma D’Aniello (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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In this paper we study the class of finite groups G whose nilpotent residual is a Hall subgroup having all subgroups normal in G .

Sull'equilibrio termoelastico di un particolare solido incomprimibile

Diego Pigozzi (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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We consider an incompressible elastic solid which admits a configuration of equilibrium having the shape of a rectangular parallelepiped C * when external forces are absent. We look for a thermoelastic transformation mapping that configuration onto a cylindrical wedge C . The problem we consider is analogous to the one where both C * and C are cylindrical crowns. This case has been considered by T. Manacorda ( 1 ) Referring C to a system of cylindrical coordinates r , ϑ and ζ , we show that the...

Su un teorema di unicità per l'equazione semilineare del calore in un dominio illimitato

Piero Bassanini (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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A periodic BVP for a semilinear elliptic-parabolic equation in an unbounded domain Ω contained in a half-space of n is considered, with Dirichlet boundary conditions on the finite part of Ω . A theorem of uniqueness of periodic solutions is proved by showing that a suitable function of the "energy" E ( x ) is subharmonic in Ω and satisfies a Phragmèn-Lindelöf growth condition at infinity.

Su una classe di gruppi finiti supersolubili

Alma D’Aniello (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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In this paper we study the class of finite groups G whose nilpotent residual is a Hall subgroup having all subgroups normal in G .

Osservazioni sullo spazio dei moduli delle curve trigonali

Fabio Bardelli, Andrea Del Centina (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Let C be an algebraic projective smooth and trigonal curve of genus g 5 . In this paper we define, in a way equivalent to that followed by A. Maroni in [1], an integer m , called the species of C , which is a birational invariant having the property that 0 m g + 2 3 and m g 0 mod(2). In section 1 we prove that for every g ( 5 ) and every m , as before, there are trigonal curves of genus g and species m . In section 2 we define the space g , 3 ; m 1 of moduli of trigonal curves of genus g and species m . We note that g , 3 ; m 1 is...

Su certi fibrati in coniche di 𝐏 2 × 𝐏 2 , alcuni dei quali unirazionali e non razionali

Andrea Del Centina, Luisella Verdi (1980)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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In this note we show that every smooth “general enough” hypersurface of bidegree ( p , 2 ) with p > 1 in 𝐏 2 × 𝐏 2 is an ordinary non rational conic-bundle. Moreover we construct an example, for p = 3 , which is unirational.

Su un teorema di unicità per l'equazione semilineare del calore in un dominio illimitato

Piero Bassanini (1985)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

A periodic BVP for a semilinear elliptic-parabolic equation in an unbounded domain Ω contained in a half-space of n is considered, with Dirichlet boundary conditions on the finite part of Ω . A theorem of uniqueness of periodic solutions is proved by showing that a suitable function of the "energy" E ( x ) is subharmonic in Ω and satisfies a Phragmèn-Lindelöf growth condition at infinity.

Sull'equilibrio termoelastico di un particolare solido incomprimibile

Diego Pigozzi (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

We consider an incompressible elastic solid which admits a configuration of equilibrium having the shape of a rectangular parallelepiped C * when external forces are absent. We look for a thermoelastic transformation mapping that configuration onto a cylindrical wedge C . The problem we consider is analogous to the one where both C * and C are cylindrical crowns. This case has been considered by T. Manacorda ( 1 ) Referring C to a system of cylindrical coordinates r , ϑ and ζ , we show that the...

Osservazioni sullo spazio dei moduli delle curve trigonali

Fabio Bardelli, Andrea Del Centina (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

Let C be an algebraic projective smooth and trigonal curve of genus g 5 . In this paper we define, in a way equivalent to that followed by A. Maroni in [1], an integer m , called the species of C , which is a birational invariant having the property that 0 m g + 2 3 and m g 0 mod(2). In section 1 we prove that for every g ( 5 ) and every m , as before, there are trigonal curves of genus g and species m . In section 2 we define the space g , 3 ; m 1 of moduli of trigonal curves of genus g and species m . We note that g , 3 ; m 1 is...

Funzioni ( p , q ) -convesse

Ennio De Giorgi, Antonio Marino, Mario Tosques (1982)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

We study a class of functions which differ essentially from those which are the sum of a convex function and a regular one and which have interesting properties related to Γ -convergence and to problems with non-convex constraints. In particular some results are given for the associated evolution equations.

Sul teorema di Cauchy-Morera per le funzioni analitiche di più variabili complesse

Gaetano Fichera (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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A Cauchy-Morera theorem is proved for a function w of n complex variables, assuming only w L l o c 1 . A related result of Bochner, concerning continuous functions, is extended to a larger function class.

Quando è possibile formare bolle in un fluido, e quando no

Epifanio G. Virga (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Bubbles are formed in a fluid by inflating a liquid film with a gas in which the pressure π ^ ( ν ) is a strictly decreasing function of the specific volume, unbounded as ν 0 + . We show that, if π ^ ( ν ) grows as fast or faster than ν - 2 / 3 as ν 0 + , then there is at least one stable equilibrium configuration of any such bubble, no matter how much gas has been used to inflate it. On the other hand, if π ^ ( ν ) grows as slowly or slower than ν - 1 / 3 as ν 0 + , then any such bubble has no equilibrium configuration, when the amount...

k—archi completi in piani di Moulton d'ordine q m

Giampaolo Menichetti (1976)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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Existence of ovals, which are contained in a class of Moulton's planes of order q m ( q odd), is proved. This class of Moulton's planes is more general than the one considered for the same purpose by Korchmáros in [2]. Furthermore some examples are given of complete q 2 -arcs, which are contained in certain Moulton's planes of order q 2 ( q even).

Sul teorema di Cauchy-Morera per le funzioni analitiche di più variabili complesse

Gaetano Fichera (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

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A Cauchy-Morera theorem is proved for a function w of n complex variables, assuming only w L l o c 1 . A related result of Bochner, concerning continuous functions, is extended to a larger function class.

Sull’esistenza di sottogruppi nilpotenti autonormalizzanti in alcuni gruppi semplici, II

Alma D'Aniello (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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We prove that in the Mathieu groups there is a unique conjugacy class of nilpotent self-normalizing subgroups, the class of the 2-Sylow subgroups. In the Janko group J 1 there are no nilpotent self-normalizing subgroups.

Su di un problema combinatorio in teoria dei gruppi

Mario Curzio, Patrizia Longobardi, Mercede Maj (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Let G be a group and n an integer 2 . We say that G has the n -permutation property ( G P n ) if, for any elements x 1 , x 2 , , x n in G , there exists some permutation σ of { 1 , 2 , , n } , σ i d . such that x 1 , x 2 , , x n = x σ ( 1 ) , x σ ( 2 ) , , x σ ( n ) . We prouve that every group G P n is an FC-nilpotent group of class n - 1 , and that a finitely generated group has the n -permutation property (for some n ) if, and only if, it is abelian by finite. We prouve also that a group G P 3 if, and only if, its derived subgroup has order at most 2.

Separabilità di L 2 ( μ ) per spazi riflessivi, μ misura gaussiana

Adriana Brogini Bratti (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Following H. Sato - Y. Okazaky we will prove that: if X is a topological vector space, locally convex and reflexive, and μ is a gaussian measure on 𝐂 ( X , X ) , then L 2 ( μ ) is separable.

Spazi di moduli di fasci aritmeticamente Cohen-Macaulay su varietà di Fano della serie principale

Maria Chiara Brambilla, Daniele Faenzi (2009)

Bollettino dell'Unione Matematica Italiana

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In the first part of the paper we complete the classification of the arithmetical Cohen-Macaulay vector bundles of rank 2 on a smooth prime Fano threefold. In the second part, we study some moduli spaces of these vector bundles, using the decomposition of the derived category of X provided by Kuznetsov, when the genus of X is 7 or 9. This allows to prove that such moduli spaces are birational to Brill-Noether varieties of vector bundles on a smooth projective curve Γ . When the second...

Sul problema pluriarmonico in un campo sferico di 𝐂 n per n 3

Maria Adelaide Sneider (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Let Σ be the boundary of the unit ball Ω of 𝐂 n . A set of second order linear partial differential operators, tangential to Σ , is explicitly given in such a way that, for n 3 , the corresponding PDE caractherize the trace of the solution of the pluriharmonic problem (either “in the large” or “local”), relative to Ω .

Quando è possibile formare bolle in un fluido, e quando no

Epifanio G. Virga (1986)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

Bubbles are formed in a fluid by inflating a liquid film with a gas in which the pressure π ^ ( ν ) is a strictly decreasing function of the specific volume, unbounded as ν 0 + . We show that, if π ^ ( ν ) grows as fast or faster than ν - 2 / 3 as ν 0 + , then there is at least one stable equilibrium configuration of any such bubble, no matter how much gas has been used to inflate it. On the other hand, if π ^ ( ν ) grows as slowly or slower than ν - 1 / 3 as ν 0 + , then any such bubble has no equilibrium configuration, when the amount...