An explicit solution of Burgers equation with stationary point source

Existence, uniqueness and regularity of the global weak solution to the Burgers equation with a reaction term is shown when the reaction term is given as a time independent point source and produces heat constantly. An explicit solution is obtained and used to show the long time asymptotic convergence of the solution to a steady state. For the heat equation case without any convection the solution diverges everywhere as time increases and hence it is the first order convection term that gives the compactness of the solution trajectory of the Burgers equation with reaction.     

An extension and simple proof of a constrained lattice fixed point theorem

We extend a result of Roth dealing with fixed points of lattice mappings which satisfy certain constraints. Presented by J. Mycielski.     

An explicit answer

The class of connectivity functions and two similarly defined classes are shown to be distinct.     

On the explicit parametric description of waves in periodic media

A method for the parameterization of the one-dimensional wave equation is proposed that makes it possible to find its solution by quadratures under an arbitrary dependence of the refraction index on the current wave phase. The form of the solution found is used to investigate the structure of the wave function for a periodic refraction index. Explicit expressions for the fundamental system of solutions and for the Floquet index are obtained. Examples of applying the proposed method to the optimal synthesis of multilayer interference mirrors and Bragg waveguides are discussed.     

Bounds for the lattice point enumerator

For the lattice point enumerator of a lattice and a convex body K we give bounds in terms of the intrinsic volumes of K and of minimal determinants of . The intrinsic volumes are the normalized Minkowski quermassintegrals and the minimal determinants are analogous functionals of .     

A lattice isomorphism theorem for cluster groups of mutation-Dynkin type An

Each quiver appearing in a seed of a cluster algebra determines a corresponding group, which we call a cluster group, which is defined via a presentation. Grant and Marsh showed that, for quivers appearing in seeds of cluster algebras of finite type, the associated cluster groups are isomorphic to finite reflection groups. As for finite Coxeter groups, we can consider parabolic subgroups of cluster groups. We prove that, in the type $A_n$ case, there exists an isomorphism between the lattice of subsets of the defining generators of the cluster group and the lattice of its parabolic subgroups. Moreover, each parabolic subgroup has a presentation given by restricting the presentation of the whole group.     

An explicit expression for the Fisher information matrix of a multiple time series process

The principal result in this paper is concerned with the derivative of a vector with respect to a block vector or matrix. This is applied to the asymptotic Fisher information matrix (FIM) of a stationary vector autoregressive and moving average time series process (VARMA). Representations which can be used for computing the components of the FIM are then obtained. In a related paper [A. Klein, A generalization of Whittle’s formula for the information matrix of vector mixed time series, Linear Algebra Appl. 321 (2000) 197-208], the derivative is taken with respect to a vector. This is obtained by vectorizing the appropriate matrix products whereas in this paper the corresponding matrix products are left unchanged.     

An explicit Schilder‐type theorem for super‐Brownian motions

Like ordinary Brownian motion, super‐Brownian motion, a central object in the theory of superprocesses, is a universal object arising in a variety of settings. Schilder‐type theorems and Cramér‐type theorems are two of the major topics for large‐deviation theory. A Schilder‐type (which is also a Cramér‐type) sample large deviation for super‐Brownian motions with a good rate function represented by a variation formula was established in 1993 and 1994; since then there have been very valuable contributions for giving an affirmative answer to the question of whether this sample large deviation holds with an explicit good rate function. In this paper, thanks to previous results on this issue and the Brownian snake, we establish such a large deviation for nonzero finite initial measures. © 2010 Wiley Periodicals, Inc.     

An explicit formula for Koecher-Maaß Dirichlet series for Eisenstein series of Klingen type

We give a reasonable expression of the Koecher-Maaß Dirichlet series for the Klingen-Eisenstein lift of an elliptic cusp form.     

Improved convexity cuts for lattice point problems

The generalized lattice point (GLP) problem provides a formulation that accommodates a variety of discrete alternative problems. In this paper, we show how to substantially strengthen the convexity cuts for the GLP problem. The new cuts are based on the identification ofsynthesized lattice point conditions to replace those that ordinarily define the cut. The synthesized conditions give an alternative set of hyperplanes that enlarge the convex set, thus allowing the cut to be shifted deeper into the solution space. A convenient feature of the strengthened cuts is the evidence of linking relationships by which they may be constructively generated from the original cuts. Geometric examples are given in the last section to show how the new cuts improve upon those previously proposed for the GLP problem.     

Asymptotics of variance of the lattice point count

The variance of the number of lattice points inside the dilated bounded set rD with random position in ℝ ^d has asymptotics ∼ r ^d−1 if the rotational average of the squared modulus of the Fourier transform of the set is O(ϰ ^−d−1). The asymptotics follow from Wiener’s Tauberian theorem.     

Mean value estimates in lattice point theory

LetQ(u) be a positive definite quadratic form inr2 variables with a real symmetric coefficient matrix of determinantD. Given a real vectorb with 0b _j <1, forx>0 letA(x) be the number of lattice points in the ellipsoidQ(u+b)x, letV(x) be the volume of this ellipsoid andP(x)=A(x)–V(x). Let . By introduction of a parameter we shall show how the treatment of estimates onP(x) and onM(x) can be unified.     

An integral characterization of random permutations. A point process approach

We consider random finite permutations and prove the following version of Thoma’s theorem in [8]: Random finite permutations which are class functions satisfy a new integration by parts formula if and only if they are given by a certain Ewens-Sütö process. The main source of inspiration for the results in this note is the fundamental work of Andras Sütö [7], from which some results are reestablished here again in the present point process approach.