Characterization of the classical domains by Caratheodory volume elements and Eisenman-Kobayashi volume elements

We give a sufficient and necessary condition that a domain is biholomorphic to the classical domain.     

Crouzeix–Raviart boundary elements

This paper establishes a foundation of non-conforming boundary elements. We present a discrete weak formulation of hypersingular integral operator equations that uses Crouzeix–Raviart elements for the approximation. The cases of closed and open polyhedral surfaces are dealt with. We prove that, for shape regular elements, this non-conforming boundary element method converges and that the usual convergence rates of conforming elements are achieved. Key ingredient of the analysis is a discrete Poincaré–Friedrichs inequality in fractional order Sobolev spaces. A numerical experiment confirms the predicted convergence of Crouzeix–Raviart boundary elements. Norbert Heuer is supported by Fondecyt-Chile under grant no. 1080044. F.-J. Sayas is partially supported by MEC-FEDER Project MTM2007-63204 and Gobierno de Aragón (Grupo Consolidado PDIE).     

Superconvergence for rectangular serendipity finite elements

Based on an orthogonal expansion and orthogonality correction in an element, superconvergence at symmetric points for any degree rectangular serendipity finite element approximation to second order elliptic problem is proved, and its behaviour up to the boundary is also discussed.     

Mixed finite elements in ℝ3

Summary We present here some new families of non conforming finite elements in ³. These two families of finite elements, built on tetrahedrons or on cubes are respectively conforming in the spacesH(curl) andH(div). We give some applications of these elements for the approximation of Maxwell's equations and equations of elasticity.First, we introduce some notations K is a tetrahedron or a cube, thevolume of which is - K is its boundary - f is a face ofK, thesurface of which is - a is an edge, the length of which is - L ² (K) is the usual Hilbert space of square integrable functions defined onK - H ^m (K) {L ²(K); L ²(K); ||m}, where =(₁, ₂, ₃) is a multi-index; ||=₁+₂+₃ - curlu u, (defined by using the distributional derivative) foru=(u ₁,u ₂,u ₃);u _iL ² (K) - H(curl) {u(L ² (K))³; curlu(L ² (K)) ³} - divu ·u - H(div) {u(L ² (K)) ³; divuL ² (K)} - D ^k u is thek-th differential operator associated tou, which is a (k+1)-multilinear operator acting on ³ - k is an index - _k is the linear space of polynomials, the degree of which is less or equal tok - _k is the group of all permutations of the set {1, 2, ...,k} - c orc will stand for any constant depending possibly on      

Elliptic elements in Möbius groups

Let G be a nonelementary subgroup of Isom(H ⁿ). In this paper we prove that if G contains elliptic elements and dim(M _G ) is even, then G is discrete if and only if WY (G) is discrete and every nonelementary subgroup of G generated by two elliptic elements is discrete. We also describe an example to show the assumption on dim(M _G ) is necessary. Supported in part by NSFC 10671059 and by Leading academic Discipline program, 211 project for Shanghai University of Finance and Economics (the 3rd phase).     

Primary elements in Prüfer lattices

In this paper we study primary elements in Prüfer lattices and characterize -lattices in terms of Prüfer lattices. Next we study weak ZPI-lattices and characterize almost principal element lattices and principal element lattices in terms of ZPI-lattices.     

Kazhdan–Lusztig polynomials of boolean elements

We give closed combinatorial product formulas for Kazhdan–Lusztig polynomials and their parabolic analogue of type q in the case of boolean elements, introduced in (Marietti in J. Algebra 295:1–26, 2006), in Coxeter groups whose Coxeter graph is a tree. Such formulas involve Catalan numbers and use a combinatorial interpretation of the Coxeter graph of the group. In the case of classical Weyl groups, this combinatorial interpretation can be restated in terms of statistics of (signed) permutations. As an application of the formulas, we compute the intersection homology Poincaré polynomials of the Schubert varieties of boolean elements.     

Does polynomial parallel volume imply convexity?

For a non-empty compact set A^d, d2, and r0, let Ar denote the set of points whose distance from A is r at the most. It is well-known that the volume, V_d(A_r), of A_r is a polynomial of degree d in the parameter r if A is convex. We pursue the reverse question and ask whether A is necessarily convex if V_d(A_r) is a polynomial in r. An affirmative answer is given in dimension d=2, counterexamples are provided for d3. A positive resolution of the question in all dimensions is obtained if the assumption of a polynomial parallel volume is strengthened to the validity of a (polynomial) local Steiner formula. Mathematics Subject Classification (2000):52A38, 28A75, 52A22, 53C65     

Does Boris-SDC conserve phase space volume?

In this paper we investigate the conservation of phase space volume of the Boris-SDC algorithm. This method provides a generic way to extend the standard, second-order accurate Lorentz force integrator commonly used for charged particles in an electric and magnetic field to a high-order method using spectral deferred corrections. For a single particle in a Penning trap and different frequencies of the electric and magnetic fields, we assess the conservation properties of the method by computing the update matrix of one step of Boris-SDC as well as its determinant. We compare the results to the convergence regions and relate them to energy conservation properties of the method. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The elements of K2(ℤs)

Let S={p₁,...,p_s} be a set of rational primes, . One has K₂(_s)K₂(_su{2} and we want to assume 2 S. It is snown that every element of K₂(_S) is a Dehnis-Stein-symbol <a,b>, 1+ab being a unit of _S.Here b can be determined concretely, depending only on S, and we obtain a normal form of the elements of K₂(Q) as Steinberg-symbols, which is unique in some way and expresses the quadratic reciprocity law.     

Interpolation theory of anisotropic finite elements and applications

Interpolation theory is the foundation of finite element methods.In this paper,after reviewing some existed interpolation theorems of anisotropic finite element methods,we present a new way to analyse the interpolation error of anisotropic elements based on Newton's formula of polynomial interpolation as well as its applications.     

Optimal transport and Perelman’s reduced volume

We show that a certain entropy-like function is convex, under an optimal transport problem that is adapted to Ricci flow. We use this to reprove the monotonicity of Perelman’s reduced volume. This research was partially supported by NSF grant DMS-0604829.     

Radial Blaschke–Minkowski homomorphisms and volume differences

In this paper we establish Minkowski, Brunn–Minkowski, and Aleksandrov-Fenchel type inequalities for volume differences of radial Blaschke–Minkowski homomorphisms.     

Dual Brunn–Minkowski inequality for volume differences

In this paper, we introduce the concepts of dual quermassintegral differences and width-integral differences, and discuss the theory of dual Brunn–Minkowski type for them. One of the results implies that for two star bodies which are dilations of each other, the dual Brunn–Minkowski inequality still holds after two arbitrary star bodies included in them being excluded, respectively.     

On outer elements of noncommutative Orlicz–Hardy spaces

Let M be a von Neumann algebra equipped with a faithful normal tracial state τ, A be a subdiagonal subalgebra of M, and let Φ be a growth function. We transfer the results of Studia Math. 217, No. 3, 265–287 (2013) to the noncommutative H^Φ(A) space case.     

High order finite volume methods for singular perturbation problems

In this paper we establish a high order finite volume method for the fourth order singular perturbation problems.In conjunction with the optimal meshes,the numerical solutions resulting from the method have optimal convergence order.Numerical experiments are presented to verify our theoretical estimates.     

Schur elements for the Ariki–Koike algebra and applications

We study the Schur elements associated to the simple modules of the Ariki–Koike algebra. We first give a cancellation-free formula for them so that their factors can be easily read and programmed. We then study direct applications of this result. We also complete the determination of the canonical basic sets for cyclotomic Hecke algebras of type G(l,p,n) in characteristic 0.