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 Subjects -> MATHEMATICS (Total: 955 journals)     - APPLIED MATHEMATICS (82 journals)    - GEOMETRY AND TOPOLOGY (20 journals)    - MATHEMATICS (706 journals)    - MATHEMATICS (GENERAL) (43 journals)    - NUMERICAL ANALYSIS (22 journals)    - PROBABILITIES AND MATH STATISTICS (82 journals) MATHEMATICS (706 journals)                  1 2 3 4 | Last

1 2 3 4 | Last

 Bollettino dell'Unione Matematica Italiana   [SJR: 0.375]   [H-I: 19]   [1 followers]  Follow        Subscription journal    ISSN (Print) 1972-6724 - ISSN (Online) 2198-2759    Published by Springer-Verlag  [2351 journals]
• Plus/minus Heegner points and Iwasawa theory of elliptic curves at
supersingular primes
• Authors: Matteo Longo; Stefano Vigni
Abstract: We extend to the supersingular case the $$\Lambda$$ -adic Euler system method (where $$\Lambda$$ is a suitable Iwasawa algebra) for Heegner points on elliptic curves that was originally developed by Bertolini in the ordinary setting. In particular, given an elliptic curve E over $$\mathbb {Q}$$ with supersingular reduction at a prime $$p\ge 5$$ , we prove results on the $$\Lambda$$ -corank of certain plus/minus p-primary Selmer groups à la Kobayashi of E over the anticyclotomic $$\mathbb {Z}_p$$ -extension of an imaginary quadratic field and on the asymptotic behaviour of p-primary Selmer groups of E when the base field varies over the finite layers of such a $$\mathbb {Z}_p$$ -extension. These theorems can be alternatively obtained by combining results of Nekovář, Vatsal and Iovita–Pollack, but do not seem to be directly available in the current literature.
PubDate: 2018-02-10
DOI: 10.1007/s40574-018-0162-4

• Weak solutions for a thermoelectric problem with power-type boundary
effects
• Authors: Luisa Consiglieri
Abstract: This paper deals with thermoelectric problems including the Peltier and Seebeck effects. The coupled elliptic and doubly quasilinear parabolic equations for the electric and heat currents are stated, respectively, under power-type boundary conditions that describe the thermal radiative effects. To verify the existence of weak solutions to this coupled problem (Theorem 1), analytical investigations for abstract multi-quasilinear elliptic-parabolic systems with nonsmooth data are presented (Theorems 2 and 3). They are essentially approximated solutions based on the Rothe method. It consists on introducing time discretized problems, establishing their existence, and then passing to the limit as the time step goes to zero. The proof of the existence of time discretized solutions relies on fixed point and compactness arguments. In this study, we establish quantitative estimates to clarify the smallness conditions.
PubDate: 2018-01-18
DOI: 10.1007/s40574-018-0159-z

• Global attractor for a smectic-A liquid crystal model in 2D
• Authors: Aibo Liu; Changchun Liu
Abstract: We consider a simplified smectic-A liquid crystal model in two dimensional bounded domain. The model consists of a Navier–Stokes equation governing the fluid velocity coupled with the transported heat flows of harmonic map. Based on the combination of the suitable dissipative estimates with the energy techniques, we established the existence of global attractor $$\mathcal {A}$$ on a suitable phase-space and proved that the system has a regular compact absorbing set.
PubDate: 2018-01-15
DOI: 10.1007/s40574-018-0156-2

• A geometric proof of the $$L^{2}$$ L 2 -singular dichotomy for orbital
measures on Lie algebras and groups
• Authors: Kathryn E. Hare; Jimmy He
Abstract: Let G be a compact, connected simple Lie group and $$\mathfrak {g}$$ its Lie algebra. It is known that if $$\mu$$ is any G-invariant measure supported on an adjoint orbit in $$\mathfrak {g}$$ , then for each integer k, the k-fold convolution product of $$\mu$$ with itself is either singular or in $$L^{2}$$ . This was originally proven by computations that depended on the Lie type of $$\mathfrak {g}$$ , as well as properties of the measure. In this note, we observe that the validity of this dichotomy is a direct consequence of the Duistermaat–Heckman theorem from symplectic geometry and that, in fact, any convolution product of (even distinct) orbital measures is either singular or in $$L^{2+\varepsilon }$$ for some $$\varepsilon >0$$ . An abstract transference result is given to show that the $$L^{2}$$ -singular dichotomy holds for certain of the G-invariant measures supported on conjugacy classes in G.
PubDate: 2018-01-11
DOI: 10.1007/s40574-017-0154-9

• Length-preserving monomorphisms for Steenrod algebras at odd primes
• Authors: Maurizio Brunetti; Adriana Ciampella
Abstract: Let p be an odd prime. In this paper we determine the group of length-preserving automorphisms for the ordinary Steenrod algebra A(p) and for $${\mathcal {B}}(p)$$ , the algebra of cohomology operations for the cohomology of cocommutative $$\mathbb {F}_p$$ -Hopf algebras. Contrarily to the $$p=2$$ case, no length-preserving strict monomorphism turns out to exist.
PubDate: 2018-01-10
DOI: 10.1007/s40574-017-0155-8

• Correction to: Irrationality issues for projective surfaces
• Authors: Francesco Bastianelli
Abstract: The purpose of this note is to fix an imprecision in Theorem 3.3 of the original paper, which affects the correctness of the statement and leads to a mistake
PubDate: 2018-01-08
DOI: 10.1007/s40574-017-0153-x

• Some uniqueness results related to L -functions
• Authors: Qi Han
Pages: 503 - 515
Abstract: In this paper, we describe a family of meromorphic functions in $$\mathbf {C}$$ from analyzing some properties of these L-functions in the extended Selberg class and show two uniqueness results of such a function, in terms of shared values with a general meromorphic function in $$\mathbf {C}$$ . In particular, we show the condition “ $$\displaystyle {1\mathsf{CM}+3\mathsf{IM}}$$ value-sharing” suffices.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0081-1
Issue No: Vol. 10, No. 4 (2017)

• Some fixed point theorems in cone modular spaces with a graph
• Authors: Sushanta Kumar Mohanta
Pages: 529 - 548
Abstract: The purpose of this paper is to obtain sufficient conditions for the existence and uniqueness of points of coincidence and common fixed points for mappings defined on cone modular spaces endowed with a graph. Our results will improve and supplement several recent results in the literature.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0086-9
Issue No: Vol. 10, No. 4 (2017)

• A remark on a theorem of Berkes
• Authors: R. P. Pakshirajan
Pages: 575 - 584
Abstract: Let x be a standard Wiener process on $$[0,\ 1]$$ , starting at the origin and with all its sample functions lying in the H $$\ddot{\text {o}}$$ lder space $$H_{\alpha }^0$$ of exponent $$\alpha ,\ 0< \alpha < \frac{1}{2}$$ . Define for $$n = 1, 2, \ldots$$ processes $$x_n$$ and $$z_n :\ x_n(t) = \frac{x(nt)}{\sqrt{n}}$$ and $$z_n(t) = \frac{x(nt)}{\sqrt{n}f(n)},\ t \in [0,\ 1]$$ where $$f(n) \rightarrow \infty$$ and $$\frac{f(n)}{\sqrt{\log \log n}} \rightarrow 0$$ . In this paper, we show that the limit set of each of the random sequences $$(x_n)$$ and ( $$z_n$$ ) of elements in $$H_{\alpha }^0$$ in its norm topology is all of the space $$H_{\alpha }^0$$ .
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0089-6
Issue No: Vol. 10, No. 4 (2017)

• A Cheney and Wulbert type lifting theorem in optimization
• Authors: T. S. S. R. K. Rao
Pages: 585 - 589
Abstract: In this paper we exhibit new classes of Banach spaces for which strong notions of optimization can be lifted from quotient spaces. Motivated by a well known result of Cheney and Wulbert on lifting of proximinality from a quotient space to a subspace, for closed subspaces, $$Z \subset Y \subset X$$ , we consider stronger forms of optimization, that Z has in X and the quotient space Y / Z has in X / Z should lead to the conclusion Y has the same property in X. The versions we consider have been studied under various names in the literature as L-proximinal subspaces or subspaces that have the strong- $$1\frac{1}{2}$$ -ball property. We give an example where the strong- $$1\frac{1}{2}$$ -ball property fails to lift to the quotient. We show that if every M-ideal in Y is a M-summand, for a finite codimensional subspace $$Z \subset Y$$ , that is a M-ideal in X with the strong- $$1\frac{1}{2}$$ -ball property in X and if Y / Z has the $$1\frac{1}{2}$$ -ball property in X / Z, then Y has the strong- $$1\frac{1}{2}$$ -ball property in X.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0090-0
Issue No: Vol. 10, No. 4 (2017)

• Addendum to the paper “Linearly topologized modules over a discrete
valuation ring”
• Authors: Patricia Couto G. Mauro; Dinamérico P. Pombo
Pages: 591 - 594
Abstract: For any discrete valuation ring R, any R-linear mapping u from an R-module E into an R-module F and any $$y_0\in F$$ , a necessary and sufficient condition for the solvability of the equation $$u(x)=y_0$$ is established, and an application of this result is presented.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0096-7
Issue No: Vol. 10, No. 4 (2017)

• Principally quasi-Baer skew Hurwitz series rings
• Authors: Kamal Paykan
Pages: 607 - 616
Abstract: A ring is quasi-Baer (respectively, right p.q.-Baer) in case the right annihilator of every (respectively, principal right) ideal is generated by an idempotent, as a right ideal. A ring R is right AIP if the right annihilator of any right ideal of R is pure as a right ideal. In this article, we study relations between the quasi-Baer, right p.q.-Baer, and right AIP properties of a ring R, and its skew Hurwitz series ring $$(HR, \alpha )$$ , where R is a ring equipped with an endomorphism $$\alpha$$ . Examples to illustrate and delimit the theory are provided.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0098-5
Issue No: Vol. 10, No. 4 (2017)

• Increase of powers in the lower order term: a come back when the source
term has a poor summability
• Authors: L. Boccardo; F. Murat
Pages: 617 - 625
Abstract: We consider a nonlinear equation with a monotone operator acting in $$W^{1, p}_0 (\Omega )$$ , a lower order term $$u u ^{n-1}$$ , and a source term in $$L^m (\Omega )$$ with a poor summability $$m > 1$$ or even $$m = 1$$ . When the power n increases and tends to $$\infty$$ , we prove that the (conveniently defined) solution of this problem converges (in a convenient sense) to the solution of the variational inequality posed on the convex set $$\{ v \in W^{1, p}_0(\Omega ) : v(x) \le 1 \}$$ .
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0093-x
Issue No: Vol. 10, No. 4 (2017)

• Stability of multivariate wave packet frames for $$L^2(\mathbb {R}^n)$$ L
2 ( R n )
• Authors: Raj Kumar; Ashok K. Sah
Pages: 637 - 647
Abstract: In this paper we study stability of multivariate wave packet frames. Necessary and sufficient conditions for a certain system to be multivariate wave packet frames are obtained.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0106-9
Issue No: Vol. 10, No. 4 (2017)

• Flows of locally finite graphs
• Authors: Hawete Hattab
Pages: 671 - 679
Abstract: Let (G, X) be a flow such that X is a locally finite graph and G is a finitely generated group. In this paper, it is shown that the following properties are equivalent: (G, X) is pointwise recurrent; (G, X) is pointwise periodic; (G, X) is pointwise almost periodic. We show that every pointwise recurrent flow of a locally finite graph is equicontinuous. We also give some qualitative properties of an equicontinuous flow.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0109-6
Issue No: Vol. 10, No. 4 (2017)

• Boundary behavior of generalized Poisson integrals on buildings of type
$$\widetilde{A}_2$$ A ~ 2
• Authors: A. M. Mantero; A. Zappa
Pages: 681 - 724
Abstract: Let $${\Delta }$$ be an affine building of type $$\widetilde{A}_2$$ and $${\Omega }$$ its maximal boundary. We prove that, for every function $$f \in L^1({\Omega }),$$ restricted convergence of the normalized generalized Poisson transform $${\mathcal {P}}_{{\chi }} f / {\mathcal {P}}_{{\chi }} 1$$ to f holds almost everywhere.
PubDate: 2017-12-01
DOI: 10.1007/s40574-016-0110-0
Issue No: Vol. 10, No. 4 (2017)

• A characterization of Hilbert $$C^*$$ C ∗ -modules over commutative
$$C^*$$ C ∗ -algebras
Abstract: Let $$\mathcal {M}$$ be a Hilbert $$C^*$$ -module. Set $$x =\big <x,x\big >^\frac{1}{2}$$ for every $$x\in \mathcal {M}$$ and $$\mathcal {C}=\overline{\{\big <x,y\big >:x,y\in \mathcal {M}\}}$$ . We prove that $$xa = x a$$ for every $$x\in \mathcal {M}$$ and $$a\in \mathcal {C}$$ if and only if $$\mathcal {C}$$ is a commutative $$C^*$$ -algebra.
PubDate: 2017-12-26
DOI: 10.1007/s40574-017-0152-y

• The convergence of some weighted means of values of a function
• Authors: Omran Kouba
Abstract: Consider a sequence $$(a_n)_{n\ge 1}$$ of complex numbers such that for some positive number p we have $$\lim _{n\rightarrow \infty }\frac{1}{n^p}\left( \sum _{k=1}^na_k\right) =\ell \in \mathbb {C}$$ . We prove that, under some mild conditions on the sequence (positivity or absolute boundedness in the mean, etc.), we have \begin{aligned} \lim _{n\rightarrow \infty } \frac{1}{n^{q}}\sum _{k=1}^nk^{q-p}a_kf\left( \frac{k}{n}\right) = p\ell \int _0^1x^{q-1}f(x)dx \end{aligned} for all $$q>0$$ and all Riemann integrable functions $$f:[0,1]\rightarrow \mathbb {C}$$ . Some applications to probability theory and to number theory are also discussed.
PubDate: 2017-12-20
DOI: 10.1007/s40574-017-0151-z

• An application of a theorem of G. Zwirner to a class of non-linear
elliptic systems in divergence form
• Authors: Giovanni Cimatti
Abstract: A theorem on the solutions of the problem $$U'(w)={\gamma }F(U(w),w), U(w_1)=u_1,\ U(w_2)=u_2$$ is applied for finding the functional solutions of the system of partial differential equations \begin{aligned} {\nabla }\cdot (a(u,w){\nabla }u)= & {} 0,\quad u=u_1{\ \hbox {on}\quad {{\Gamma }}_1},\quad u=u_2{\ \hbox {on}\quad {{\Gamma }}_2},\quad \frac{{\partial }u}{{\partial }n}=0{\ \hbox {on}\quad {{\Gamma }}_3} \\ {\nabla }\cdot (b(u,w){\nabla }w)= & {} 0,\quad w=w_1{\ \hbox {on}\quad {{\Gamma }}_1},\quad w=w_2{\ \hbox {on}\quad {{\Gamma }}_2},\quad \frac{{\partial }w}{{\partial }n}=0{\ \hbox {on}\quad {{\Gamma }}_3}. \end{aligned} The problem of existence and uniqueness of solutions is considered.
PubDate: 2017-12-12
DOI: 10.1007/s40574-017-0150-0

• MasterPVA and WAlg: Mathematica packages for Poisson vertex algebras and
classical affine $${\mathcal {W}}$$ W -algebras
• Authors: Matteo Casati; Daniele Valeri
Abstract: We give an introduction to the Mathematica packages MasterPVA and MasterPVAmulti used to compute $$\lambda$$ -brackets in Poisson vertex algebras, which play an important role in the theory of infinite-dimensional Hamiltonian systems. As an application, we give an introduction to the Mathematica package WAlg aimed to compute the $$\lambda$$ -brackets among the generators of classical affine $${\mathcal {W}}$$ -algebras. The use of these packages is shown by providing some explicit examples.
PubDate: 2017-12-09
DOI: 10.1007/s40574-017-0146-9

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