共查询到20条相似文献,搜索用时 31 毫秒
1.
Abdellatif Moudafi 《Numerical Functional Analysis & Optimization》2013,34(1):39-47
This article is concerned with a generalization of the hybrid steepest descent method from variational inequalities to the multivalued case. This will be reached by replacing the multivalued operator by its Yosida approximate, which is always Lipschitz continuous. It is worth mentioning that the hybrid steepest descent method is an algorithmic solution to variational inequality problems over the fixed point set of certain nonexpansive mappings and has remarkable applicability to the constrained nonlinear inverse problems like image recovery and MIMO communication systems (see, e.g., [9, 10]). 相似文献
2.
Anna Giordano Bruno 《代数通讯》2013,41(11):4155-4174
For a set Γ, a function λ: Γ → Γ and a nontrivial abelian group K, the \emphgeneralized shift σλ: K Γ → K Γ is defined by (x i ) i∈Γ ? (x λ(i)) i∈Γ [3]. In this article we compute the algebraic entropy of σλ; it is either zero or infinite, depending exclusively on the properties of λ. This solves two problems posed in [2]. 相似文献
3.
《偏微分方程通讯》2013,38(5-6):605-641
ABSTRACT We show that the Klein–Gordon–Schrödinger system in one, two, and three dimensions has a global solution below the energy space. The proof uses the I-method recently introduced by Colliander et al. (2001) and mixed type Strichartz estimates for the solutions of Schrödinger and Klein–Gordon equations, respectively. 相似文献
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We prove that there are no networks homeomorphic to the Greek “Theta” letter (a double cell) embedded in the plane with two triple junctions with angles of 120 degrees, such that under the motion by curvature they are self–similarly shrinking.This fact completes the classification of the self–similarly shrinking networks in the plane with at most two triple junctions, see [5, 10, 25, 2]. 相似文献
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Takahiko Furuya 《代数通讯》2013,41(8):2926-2942
Let Λ be a finite-dimensional (D, A)-stacked monomial algebra. In this article, we give necessary and sufficient conditions for the variety of a simple Λ-module to be nontrivial. This is then used to give structural information on the algebra Λ, as it is shown that if the variety of every simple module is nontrivial, then Λ is a D-Koszul monomial algebra. We also provide examples of (D, A)-stacked monomial algebras which are not self-injective but nevertheless satisfy the finite generation conditions (Fg1) and (Fg2) of [4], from which we can characterize all modules with trivial variety. 相似文献
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The results of [7] and [2] gave a recursive construction for all quasi-hereditary and standardly stratified algebras starting with local algebras and suitable bimodules. Using the notion of stratifying pairs of subcategories, introduced in [3], we generalize these earlier results to construct recursively all CPS-stratified algebras. 相似文献
8.
It is unknown whether a power series ring over a strongly clean ring is, itself, always strongly clean. Although a number of authors have shown that the above statement is true in certain special cases, the problem remains open, in general. In this article, we look at a class of strongly clean rings, which we call the optimally clean rings, over which power series are strongly clean. This condition is motivated by work in [10] and [11]. We explore the properties of optimally clean rings and provide many examples, highlighting the role that this new class of rings plays in investigating the question of strongly clean power series. 相似文献
9.
Stacy L. Beun 《代数通讯》2013,41(4):1334-1352
Symmetric k-varieties are a generalization of symmetric spaces to general fields. Orbits of a minimal parabolic k-subgroup acting on a symmetric k-variety are essential in the study of symmetric k-varieties and their representations. In this article, we present the classification of these orbits for the group SL(2,k) for a number of base fields k, including finite fields and the 𝔭-adic numbers. We use the characterization in Helminck and Wang (1993), which requires one to first classify the orbits of the θ-stable maximal k-split tori under the action of the k-points of the fixed point group. 相似文献
10.
In this paper we consider a kinetic model for alignment of cells or filaments with probabilistic turning. For this equation existence of solutions is known, see [6]. To understand its qualitative behavior, especially with respect to the selection of orientations and mass distributions for long times, the model is approximated by a diffusion equation in the limit of small deviations of the interactions between the cell bundles. For this new equation existence of steady states is shown. In contrast to the kinetic equation discussed in [6] with deterministic turning, where local stability of two opposite orientations was shown but no selection of mass could be observed, for the new approximating problem with probabilistic turning additionally mass selection takes place. In the limit of small diffusion, steady states can only be constructed, if the aligning masses are either equal or the total mass is concentrated in one direction. By numerical simulations we tested stability of these steady states and for situations with 4 symmetrically placed smooth distributions of alignment. Convergence of the numerical code was proved. The simulations suggest, that only the 2- and the 1-peak steady states can be stable, whereas the 4 peak steady state is always unstable. We conjecture that the noise in the system is responsible for this final selection of masses. There exist other steady states with an arbitrary number of aligned bundles of cells or filaments, but we suspect that, as numerically shown for the 4 peak case, these multi-peak states are all unstable. 相似文献
11.
We investigate further the existence of solutions to kinetic models of chemotaxis. These are nonlinear transport-scattering equations with a quadratic nonlinearity which have been used to describe the motion of bacteria since the 80's when experimental observations have shown they move by a series of ‘run and tumble’. The existence of solutions has been obtained in several papers Chalub et al. (2004), Hwang et al. (2005a b) using direct and strong dispersive effects. Here, we use the weak dispersion estimates of Castella and Perthame (1996) to prove global existence in various situations depending on the turning kernel. In the most difficult cases, where both the velocities before and after tumbling appear, with the known methods, only Strichartz estimates can give a result, with a smallness assumption. 相似文献
12.
Francesc Bars 《代数通讯》2013,41(6):2160-2170
We determine the group structure of the normalizer of Γ0(N) in SL 2(?) modulo Γ0(N). These results correct the Atkin–Lehner statement (Atkin and Lehner, 1970, Theorem 8). 相似文献
13.
ABSTRACT All the 62 monomial elements in the canonical basis B of the quantized enveloping algebra for type A 4 have been determined in Hu et al. (2003). According to Lusztig's idea (Lusztig, 1992), the elements in the canonical basis B consist of monomials and linear combinations of monomials (for convenience, we call them polynomials). In this note, we compute all the 144 polynomial elements in one variable in the canonical basis B of the quantized enveloping algebra for type A 4 based on our joint note Hu et al. (2003). We conjecture that there are other polynomial elements in two or three variables in the canonical basis B, which include independent variables and dependent variables. Moreover, it is conjectured that there are no polynomial elements in the canonical basis B with four or more variables. 相似文献
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Abstract We develop two parsimonious models for pricing multi-name credit derivatives. We derive closed form expression for the loss distribution, which then can be used in determining the prices of tranche and index swaps and more exotic derivatives on these contracts. Our starting point is the model of Ding et al., 2008, which takes the loss process as a time-changed birth process. We introduce stochastic parameter variations into the intensity of the loss process and use the multi-time scale approach of Fouque et al., 2003 and obtain explicit perturbation approximations to the loss distribution. We demonstrate the competence of our approach by calibrating it to the CDX index data. 相似文献
17.
Fernando Fantino 《代数通讯》2013,41(10):4426-4434
We classify the conjugacy classes of p-cycles of type D in alternating groups. This finishes the open cases in [3]. Also we determine all the subracks of those conjugacy classes which are not of type D. 相似文献
18.
In this article, we provide a semilocal analysis for the Steffensen-type method (STTM) for solving nonlinear equations in a Banach space setting using recurrence relations. Numerical examples to validate our main results are also provided in this study to show that STTM is faster than other methods ([7, 13]) using similar convergence conditions. 相似文献
19.
Enrico Gregorio 《代数通讯》2013,41(4):1137-1146
ABSTRACT In this note,we answer a question of Hong et al. (2003) by proving that if α is a monomorphism of a reduced ring R, and R is α-skew Armendariz, then R is α-rigid. 相似文献
20.
Sara Madariaga 《代数通讯》2017,45(1):183-197
In this paper, we define pre-Malcev algebras and alternative quadri-algebras and prove that they generalize pre-Lie algebras and quadri-algebras, respectively, to the alternative setting. We use the results and techniques from [4, 14] to discuss and give explicit computations of different constructions in terms of bimodules, splitting of operations, and Rota–Baxter operators. 相似文献