Displaying similar documents to “Commutative cancellative semigroups and rational vector spaces”

Bounded Solutions for Some Dirichlet Problems with L 1 ( Ω ) Data

Tommaso Leonori (2007)

Bollettino dell'Unione Matematica Italiana

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In this paper we prove the existence of a solution for a problem whose model is: { - Δ u + u σ - | u | = γ | u | 2 + f ( x ) in  Ω u = 0 on  Ω with f ( x ) in L 1 ( Ω ) and σ , γ > 0 .

Sufficient Conditions for Integrability of Distortion Function Kf 1

Costantino Capozzoli (2009)

Bollettino dell'Unione Matematica Italiana

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Assume that Ω , Ω are planar domains and f : Ω onto Ω is a homeomorphism belonging to Sobolev space W loc 1 , 1 ( Ω ; 2 ) with finite distortion. We prove that if the distortion function K f of f satisfies the condition dist EXP ( K f , L ) < 1 , then the distortion function K f - 1 of f - 1 belongs to L loc 1 ( Ω ) . We show that this result is sharp in sense that the conclusion fails if dist EXP ( K f , L ) = 1 . Moreover, we prove that if the distortion function K f satisfies the condition dist EXP ( K f , L ) = λ for some λ > 0 , then K f - 1 belongs to L loc p ( Ω ) for every p ( 0 , 1 2 λ ) . As special case of this result we show that if...

An Elliptic Problem with a Lower Order Term Having Singular Behaviour

Daniela Giachetti, François Murat (2009)

Bollettino dell'Unione Matematica Italiana

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We prove the existence of distributional solutions to an elliptic problem with a lower order term which depends on the solution u in a singular way and on its gradient D u with quadratic growth. The prototype of the problem under consideration is { - Δ u + λ u = ± | D u | 2 | u | k + f in Ω , u = 0 on Ω , where λ > 0 , k > 0 ; f ( x ) L ( Ω ) , f ( x ) 0 (and so u 0 ). If 0 < k < 1 , we prove the existence of a solution for both the "+" and the "-" signs, while if k 1 , we prove the existence of a solution for the "+" sign only.

A Note on the Ground State Solutions for the Nonlinear Schrödinger-Maxwell Equations

A. Azzollini, A. Pomponio (2009)

Bollettino dell'Unione Matematica Italiana

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In this paper we study the nonlinear Schrödinger-Maxwell equations { - Δ u + V ( x ) u + ϕ u = | u | p - 1 u in 3 , - Δ ϕ = u 2 in 3 . If V is a positive constant, we prove the existence of a ground state solution ( u , ϕ ) for 2 < p < 5 . The non-constant potential case is treated for 3 < p < 5 , and V possibly unbounded below.

On the Dirichlet Problem with Orlicz Boundary Data

Gabriella Zecca (2007)

Bollettino dell'Unione Matematica Italiana

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Let us consider a Young's function Φ : + + satisfying the Δ 2 condition together with its complementary function Ψ , and let us consider the Dirichlet problem for a second order elliptic operator in divergence form: { L u = 0 in  B u | B = f B the unit ball of n . In this paper we give a necessary and sufficient condition for the L ϕ -solvability of the problem, where L ϕ is the Orlicz Space generated by the function Φ . This means solvability for f L Φ in the sense of [5], [8], where the case Φ ( t ) = t p is treated. ...

Persistence of Coron’s solution in nearly critical problems

Monica Musso, Angela Pistoia (2007)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

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We consider the problem - Δ u = u N + 2 N - 2 + λ in Ω ε ω , u &gt; 0 in Ω ε ω , u = 0 on Ω ε ω , where Ω and ω are smooth bounded domains in N , N 3 , ε &gt; 0 and λ . We prove that if the size of the hole ε goes to zero and if, simultaneously, the parameter λ goes to zero at the appropriate rate, then the problem has a solution which blows up at the origin.

Cohomology of Tango bundle on 5

Daniele Faenzi (2006)

Bollettino dell'Unione Matematica Italiana

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The Tango bundle T is defined as the pull-back of the Cayley bundle over a smooth quadric Q 5 in 6 via a map f existing only in characteristic 2 and factorizing the Frobenius φ . The cohomology of T is computed in terms of S C , φ * ( C ) , Sym 2 ( C ) and C , which we handle with Borel-Bott-Weil theorem.

Asymptotics for Eigenvalues of a Non-Linear Integral System

D.E. Edmunds, J. Lang (2008)

Bollettino dell'Unione Matematica Italiana

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Let I = [ a , b ] , let 1 < q , p < , let u and v be positive functions with u L p ( I ) e v L q ( I ) and let T : L p ( I ) L q ( I ) be the Hardy-type operator given by ( T f ) ( x ) = v ( x ) a x f ( t ) u ( t ) d t , x I . We show that the asymptotic behavior of the eigenvalues λ of the non-linear integral system g ( x ) = ( T F ) ( x ) ( f ( x ) ) ( p ) = λ ( T * g ( p ) ) ) ( x ) (where, for example, t ( p ) = | t | p - 1 sgn ( t ) is given by lim n n λ ^ n ( T ) = c p , q I ( u v ) r ) 1 / r d t 1 / r , for 1 < p < q < lim n n λ ˇ n ( T ) = c p , q I ( u v ) r d t 1 / r for 1 < q < p < Here r = 1 p + 1 p , c p , q is an explicit constant depending only on p and q , λ ^ ( T ) = max ( s p n ( T , p , q ) ) , λ ˇ n ( T ) = min ( s p n ( T , p , q ) ) where s p n ( T , p , q ) stands for the set of all eigenvalues λ corresponding to eigenfunctions g with n zeros.

Sobolev versus Hölder local minimizers and existence of multiple solutions for a singular quasilinear equation

Jacques Giacomoni, Ian Schindler, Peter Takáč (2007)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

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We investigate the following quasilinear and singular problem, t o 2 . 7 c m - Δ p u = λ u δ + u q in Ω ; u | Ω = 0 , u &gt; 0 in Ω , t o 2 . 7 c m (P) where Ω is an open bounded domain with smooth boundary, 1 &lt; p &lt; , p - 1 &lt; q p * - 1 , λ &gt; 0 , and 0 &lt; δ &lt; 1 . As usual, p * = N p N - p if 1 &lt; p &lt; N , p * ( p , ) is arbitrarily large if p = N , and p * = if p &gt; N . We employ variational methods in order to show the existence of at least two distinct (positive) solutions of problem (P) in W 0 1 , p ( Ω ) . While following an approach due to Ambrosetti-Brezis-Cerami, we need to prove two new results of separate interest: a strong comparison principle...

Contracting endomorphisms and dualizing complexes

Saeed Nasseh, Sean Sather-Wagstaff (2015)

Czechoslovak Mathematical Journal

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We investigate how one can detect the dualizing property for a chain complex over a commutative local Noetherian ring R . Our focus is on homological properties of contracting endomorphisms of R , e.g., the Frobenius endomorphism when R contains a field of positive characteristic. For instance, in this case, when R is F -finite and C is a semidualizing R -complex, we prove that the following conditions are equivalent: (i) C is a dualizing R -complex; (ii) C 𝐑 Hom R ( n R , C ) for some n > 0 ; (iii) G C -dim n R < and C is derived...

Isomorphisms of Royden Type Algebras Over 𝕊 1

Teresa Radice, Eero Saksman, Gabriella Zecca (2009)

Bollettino dell'Unione Matematica Italiana

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Let 𝕊 1 and 𝔻 be the unit circle and the unit disc in the plane and let us denote by 𝒜 ( 𝕊 1 ) the algebra of the complex-valued continuous functions on 𝕊 1 which are traces of functions in the Sobolev class W 1 , 2 ( 𝔻 ) . On 𝒜 ( 𝕊 1 ) we define the following norm u = u L ( 𝕊 1 ) + ( 𝔻 | u ~ | 2 ) 1 / 2 where is the harmonic extension of u to 𝔻 . We prove that every isomorphism of the functional algebra 𝒜 ( 𝕊 1 ) is a quasitsymmetric change of variables on 𝕊 1 .

On the Anderson-Badawi ω R [ X ] ( I [ X ] ) = ω R ( I ) conjecture

Peyman Nasehpour (2016)

Archivum Mathematicum

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Let R be a commutative ring with an identity different from zero and n be a positive integer. Anderson and Badawi, in their paper on n -absorbing ideals, define a proper ideal I of a commutative ring R to be an n -absorbing ideal of R , if whenever x 1 x n + 1 I for x 1 , ... , x n + 1 R , then there are n of the x i ’s whose product is in I and conjecture that ω R [ X ] ( I [ X ] ) = ω R ( I ) for any ideal I of an arbitrary ring R , where ω R ( I ) = min { n : I is an n -absorbing ideal of R } . In the present paper, we use content formula techniques to prove that their conjecture is true, if one of the following...

Subclasses of typically real functions determined by some modular inequalities

Leopold Koczan, Katarzyna Trąbka-Więcław (2010)

Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica

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Let T be the family of all typically real functions, i.e. functions that are analytic in the unit disk Δ : = { z : | z | < 1 } , normalized by f ( 0 ) = f ' ( 0 ) - 1 = 0 and such that Im z Im f ( z ) 0 for z Δ . Moreover, let us denote: T ( 2 ) : = { f T : f ( z ) = - f ( - z ) for z Δ } and T M , g : = { f T : f M g in Δ } , where M > 1 , g T S and S consists of all analytic functions, normalized and univalent in Δ .We investigate  classes in which the subordination is replaced with the majorization and the function g is typically real but does not necessarily univalent, i.e. classes { f T : f M g in Δ } , where M > 1 , g T , which we denote...

Eisenstein ideal and reducible λ -adic Representations Unramified Outside a Finite Number of Primes.

Miriam Ciavarella (2006)

Bollettino dell'Unione Matematica Italiana

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The object of this note is to study certain 2-dimensional λ -adic representations of Gal ( Q ¯ / Q ) ; fixed p 1 , , p n distinct primes, we will consider representations ρ : G G L 2 ( A ) , given by the matrix ρ = ( a b c d ) which are unramified outside p 1 , , p n , and the residue characteristic of λ , which are a product of m representations over finite extensions of the ring of Witt vectors of the residue field and which are reducible modulo λ . In analogy with the theory of the modular representations, we will introduce the analogue of Mazur's Hecke...

The Schreier Property and Gauss' Lemma

Daniel D. Anderson, Muhammad Zafrullah (2007)

Bollettino dell'Unione Matematica Italiana

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Let D be an integral domain with quotient field D . Recall that D is Schreier if D is integrally closed and for all x , y , z D { 0 } , x | y z implies that x = r s where r | y e s | z . A GCD domain is Schreier. We show that an integral domain D is a GCD domain if and only if (i) for each pair a , b D { 0 } , there is a finitely generated ideal B such that a D b D = B v and (ii) every quadratic in D [ X ] that is a product of two linear polynomials in K [ X ] is a product of two linear polynomials in D [ X ] . We also show that D is Schreier if and only if every...

Correctors for Parabolic Equations in a Heterogeneous Fibered Medium

Mourad Sfaxi, Ali Sili (2007)

Bollettino dell'Unione Matematica Italiana

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We study the problem of correctors in the framework of the homogenization of linear parabolic equations posed in a heterogeneous medium Ω made of two materials. The first one is located in a set F ϵ of cylindrical parallel fibers periodically distributed with a period of size ϵ , and the second one is located in the "matrix" M ϵ = Ω F ϵ . The ratio between the conductivity coefficients of the two materials is of order 1 / ϵ 2 . After writing the homogenized problem, we give a corrector result and prove...

Conductor and separating degrees for sets of points in r and in 1 × 1

Lucia Marino (2006)

Bollettino dell'Unione Matematica Italiana

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We attempt to generalize conductor degree's results, known in 2 , to the case of 0-dimensional schemes of r . In the first part of this paper, we consider the problem of characterizing the sequences generators's degrees of the conductor which are compatible with a fixed postulation (or Hilbert function) for a set of points in r and we determine the conductor degree of every point in a r -partial intersection. In addition, we define the separating degree of a point for a 0-dimensional subscheme...

A New L 1 -Lower Semicontinuity Result

Daniele Graziani (2007)

Bollettino dell'Unione Matematica Italiana

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The aim of this work is to prove a chain rule and an L 1 -lower semicontinuity theorems for integral functional defined on B V ( Ω ) . Moreover we apply this result in order to obtain new relaxation and Γ -convergence result without any coerciveness and any continuity assumption of the integrand f ( x , s , p ) with respect to the variable s .

The importance of rational extensions

Frans Loonstra (1988)

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

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The rational completion M ¯ of an R -module M can be characterized as a τ M -injective hull of M with respect to a (hereditary) torsion functor τ M depending on M . Properties of a torsion functor depending on an R -module M are studied.

A Montel Type Result for Subharmonic Functions

R. Supper (2009)

Bollettino dell'Unione Matematica Italiana

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This article is devoted to sequences ( u n ) n of subharmonic functions in N , with finite order, whose means J u n ( r ) (over spheres centered at the origin, with radius r) satisfy such a condition as: r > 0 , A r > 0 such that J u n ( r ) A r , n 𝐍 . The paper investigates under which conditions one may extract a pointwise or uniformly convergent subsequence.

Congruences between modular forms and related modules

Miriam Ciavarella (2006)

Bollettino dell'Unione Matematica Italiana

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We fix a prime and let M be an integer such that M ; let f S 2 ( Γ 1 ( M 2 ) ) be a newform supercuspidal of fixed type at and special at a finite set of primes. For an indefinite quaternion algebra over Q , of discriminant dividing the level of f , there is a local quaternionic Hecke algebra T associated to f . The algebra T acts on a module M f coming from the cohomology of a Shimura curve. Applying the Taylor-Wiles criterion and a recent Savitt's theorem, T is the universal deformation ring of a global...

Threefolds with Kodaira Dimension 0 or 3

Ezio Stagnaro (2007)

Bollettino dell'Unione Matematica Italiana

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Using the theory of adjoints and pluricanonical adjoints, we construct three nonsingular threefolds, as desingularizations of degree six hypersurfaces in 4 , having the irregularities q 1 = q 2 = 0 and the following periodical sequences of plurigenera respectively ( p g , P 2 , P 3 , , P m , ) = ( 0 , 0 , 1 , 0 , 0 , 1 , ) , ( 0 , 0 , 0 , 1 , 0 , 0 , 0 , 1 , ) , ( 0 , 0 , 0 , 0 , 1 , 0 , 0 , 0 , 0 , 1 , ) . In the Appendix, starting from the second above-mentioned example, we construct a threefold of general type with q q 1 = q 2 = 0 , p g = 1 , P 2 = 2 whose m-canonical transformation is birational if and only if m 11 .

Adding or removing an element from a pseudo-symmetric numerical semigroup

J. C. Rosales (2006)

Bollettino dell'Unione Matematica Italiana

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If S is a pseudo-symmetric numerical semigroup, g is its Frobenius number and S is a minimal generator of S , then S { g } , S { g } S and S { 1 2 g , g } are also numerical semigroups. In this paper we study these constructions.

The Martingale Problem in Hilbert Spaces

Giuseppe Da Prato, Luciano Tubaro (2008)

Bollettino dell'Unione Matematica Italiana

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We consider an SPDE in a Hilbert space H of the form d X ( t ) = ( A X ( t ) + b ( X ( t ) ) ) d t + σ ( X ( t ) ) d W ( t ) , X ( 0 ) = x H and the corresponding transition semigroup P t f ( x ) = 𝔼 [ f ( X ( t , x ) ) ] . We define the infinitesimal generator L ¯ of P t through the Laplace transform of P t as in [1]. Then we consider the differential operator L φ = 1 2 Tr [ σ ( x ) σ * ( x ) D 2 φ ] + b ( x ) , D φ defined on a suitable set V of regular functions. Our main result is that if V is a core for L ¯ , then there exists a unique solution of the martingale problem defined in terms of L . Application to the Ornstein-Uhlenbeck equation and to some regular...

On the projective genus of surfaces

Pietro Sabatino (2006)

Bollettino dell'Unione Matematica Italiana

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Let X N be a smooth irreducible non degenerate surface over the complex numbers, N 4 . We define the projective genus of X , denoted by P G ( X ) , as the geometric genus of the singular curve of the projection of X from a general linear subspace of codimension four. Denote by g ( X ) the sectional genus of X . In this paper we conjecture that the only surfaces for which P G ( X ) = g ( X ) - 1 are the del Pezzo surface in 4 , in 5 and a conic bundle of degree 5 in 4 . We prove that for N 5 if P G ( X ) = g ( X ) - 1 + λ , λ a non negative integer, then g ( X ) λ + 1 + α where...

Explicit birational geometry of threefolds of general type, I

Jungkai A. Chen, Meng Chen (2010)

Annales scientifiques de l'École Normale Supérieure

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Let V be a complex nonsingular projective 3-fold of general type. We prove P 12 ( V ) : = dim H 0 ( V , 12 K V ) &gt; 0 and P m 0 ( V ) &gt; 1 for some positive integer m 0 24 . A direct consequence is the birationality of the pluricanonical map ϕ m for all m 126 . Besides, the canonical volume Vol ( V ) has a universal lower bound ν ( 3 ) 1 63 · 126 2 .

2-Cohomology of semi-simple simply connected group-schemes over curves defined over p -adic fields

Jean-Claude Douai (2013)

Journal de Théorie des Nombres de Bordeaux

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Let X be a proper, smooth, geometrically connected curve over a p -adic field k . Lichtenbaum proved that there exists a perfect duality: Br ( X ) × Pic ( X ) / between the Brauer and the Picard group of X , from which he deduced the existence of an injection of Br ( X ) in P X Br ( k P ) where P X and k P denotes the residual field of the point P . The aim of this paper is to prove that if G = G ˜ is an X e t - scheme of semi-simple simply connected groups (s.s.s.c groups), then we can deduce from Lichtenbaum’s results...

Relaxation and gamma-convergence of supremal functionals

Francesca Prinari (2006)

Bollettino dell'Unione Matematica Italiana

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We prove that the Γ -limit in L μ of a sequence of supremal functionals of the form F k ( u ) = μ - ess sup Ω f k ( x , u ) is itself a supremal functional. We show by a counterexample that, in general, the function which represents the Γ -lim F ( , B ) of a sequence of functionals F k ( u , B ) = μ - ess sup B f k ( x , u ) can depend on the set B and wegive a necessary and sufficient condition to represent F in the supremal form F ( u , B ) = μ - ess sup B f ( x , u ) . As a corollary, if f represents a supremal functional, then the level convex envelope of f represents its weak* lower semicontinuous envelope. ...

Composite rational functions expressible with few terms

Clemens Fuchs, Umberto Zannier (2012)

Journal of the European Mathematical Society

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We consider a rational function f which is ‘lacunary’ in the sense that it can be expressed as the ratio of two polynomials (not necessarily coprime) having each at most a given number of terms. Then we look at the possible decompositions f ( x ) = g ( h ( x ) ) , where g , h are rational functions of degree larger than 1. We prove that, apart from certain exceptional cases which we completely describe, the degree of g is bounded only in terms of (and we provide explicit bounds). This supports and quantifies...

Geometry of Syzygies via Poncelet Varieties

Giovanna Ilardi, Paola Supino, Jean Vallès (2009)

Bollettino dell'Unione Matematica Italiana

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We consider the Grassmannian 𝔾 r ( k , n ) of ( k + 1 ) -dimensional linear subspaces of V n = H 0 ( 1 , 𝒪 1 ( n ) ) . We define 𝔛 k , r , d as the classifying space of the k -dimensional linear systems of degree n on 1 , whose bases realize a fixed number r of polynomial relations of fixed degree d , say r syzygies of degree d . Firstly, we compute the dimension of 𝔛 k , r , d . In the second part we make a link between 𝔛 k , r , d and the Poncelet varieties. In particular, we prove that the existence of linear syzygies implies the existence of singularities on the...