http://en.redtram.com/ News on "Mathematics"  everywhere Copyright (c) 2008 RedTram. All rights reserved. webmaster@redtram.com (RedTram) en Fri, 29 Aug 2008 23:02:11 GMT 300 100 50 http://en.redtram.com/ http://img.en.redtram.com/rsslogo.gif 6592 | Well-posedness of the three-dimensional Lagrangian averaged Navier-Stokes equations. (arXiv:math/0406205v2 [math.AP] UPDATED) http://en.redtram.com/go/149319939/top100/ 149319939 In this dissertation, we study the well-posedness of the three-dimensionalLagrangian averaged Navier-Stokes (LANS-$\alpha$) equations. There are twotypes of LANS-$\alpha$ equations: the anisotropic version in which thefluctuation tensor is a dynamic variable that is coupled with the evolutionequations for the mean Fri, 29 Aug 2008 18:05:40 GMT http://en.redtram.com/go/149319939/top100/ 6592 | Remarks on KdV-type Flows on Star-Shaped Curves. (arXiv:0808.3593v1 [nlin.SI] CROSS LISTED) http://en.redtram.com/go/149319943/top100/ 149319943 We study the relation between the centro-affine geometry of star-shapedplanar curves and the projective geometry of parametrized maps into $\RP^1$. Weshow that projectivization induces a map between differential invariants and abi-Poisson map between Hamiltonian structures. We also show that a Fri, 29 Aug 2008 18:05:40 GMT http://en.redtram.com/go/149319943/top100/ 6592 | The moduli space of curves is rigid. (arXiv:math/0509567v2 [math.AG] UPDATED) http://en.redtram.com/go/149319924/top100/ 149319924 We prove that the moduli stack of stable curves of genus g with n markedpoints is rigid, i.e., has no infinitesimal deformations. This confirms thefirst case of a principle proposed by Kapranov. It can also be viewed as aversion of Fri, 29 Aug 2008 18:05:38 GMT http://en.redtram.com/go/149319924/top100/ 6592 | Mednykh's Formula via Lattice Topological Quantum Field Theories. (arXiv:math/0703073v3 [math.QA] UPDATED) http://en.redtram.com/go/149319922/top100/ 149319922 Mednykh proved that for any finite group G and any orientable surface S,there is a formula for #Hom(pi_1(S), G) in terms of the Euler characteristic ofS and the dimensions of the irreducible representations of G. A similar formulain the nonorientable Fri, 29 Aug 2008 18:05:38 GMT http://en.redtram.com/go/149319922/top100/ 6592 | Groups with a Character of Large Degree. (arXiv:math/0603239v3 [math.GR] UPDATED) http://en.redtram.com/go/149319916/top100/ 149319916 Let G be a finite group of order n and V an irreducible representation overthe complex numbers of dimension d. For some nonnegative number e, we haven=d(d+e). If e is small, then the character of V has unusually large degree. Fri, 29 Aug 2008 18:05:37 GMT http://en.redtram.com/go/149319916/top100/ 6592 | Large eddy approximation of turbulent flow in DSC schemes. (arXiv:math/0603704v6 [math.NA] UPDATED) http://en.redtram.com/go/149319918/top100/ 149319918 Large eddy approximation of turbulent flow is given a natural setting withinthe DSC framework of computational fluid dynamics. Periodic cellularcoarse-graining prevents the nodal flow from piling up and preserves its largepatterns. The coarsening operations are consistent with the near-fieldinteraction principle Fri, 29 Aug 2008 18:05:37 GMT http://en.redtram.com/go/149319918/top100/ 6592 | A Morse complex for Lorentzian geodesics. (arXiv:math/0605261v2 [math.DG] UPDATED) http://en.redtram.com/go/149319919/top100/ 149319919 We prove the Morse relations for all geodesics connecting two non-conjugatepoints on a class of globally hyperbolic Lorentzian manifolds. We overcome thedifficulties coming from the fact that the Morse index of every geodesic isinfinite, and from the lack of the Fri, 29 Aug 2008 18:05:37 GMT http://en.redtram.com/go/149319919/top100/ 6592 | Schur-Weyl duality in positive characteristic. (arXiv:math/0610591v3 [math.RT] UPDATED) http://en.redtram.com/go/149319920/top100/ 149319920 Complete proofs of Schur-Weyl duality in positive characteristic are scarcein the literature. The purpose of this survey is to write out the details ofsuch a proof, deriving the result in positive characteristic from the classicalresult in characteristic zero, using only Fri, 29 Aug 2008 18:05:37 GMT http://en.redtram.com/go/149319920/top100/ 6592 | A non-homogeneous orbit of a diagonal subgroup. (arXiv:0707.2920v2 [math.DS] UPDATED) http://en.redtram.com/go/149319909/top100/ 149319909 Let G=SL(n,R) with n>5. We construct examples of lattices Gamma of G,subgroup A of the diagonal group and points x in G/Gamma such that the closureof the orbit Ax is not homogeneous but does not factors through the action of Fri, 29 Aug 2008 18:05:36 GMT http://en.redtram.com/go/149319909/top100/ 6592 | Analytic crossing probabilities for certain barriers by Brownian motion. (arXiv:0704.2826v2 [math.PR] UPDATED) http://en.redtram.com/go/149319905/top100/ 149319905 We calculate crossing probabilities and one-sided last exit time densitiesfor a class of moving barriers on an interval $[0,T]$ via Schwartzdistributions. We derive crossing probabilities and first hitting timedensities for another class of barriers on $[0,T]$ by proving a Schwartzdistribution Fri, 29 Aug 2008 18:05:36 GMT http://en.redtram.com/go/149319905/top100/ 6592 | Explicit HRS-Tilting. (arXiv:0704.1008v2 [math.RT] UPDATED) http://en.redtram.com/go/149319839/top100/ 149319839 For an abelian category $A$ equipped with a torsion pair, we give an explicitdescription for the abelian category $B$ introduced by Happel-Reiten-Smalo, andalso for the category of chain complexes $Ch(B)$ and the derived category$D(B)$ of $B$. We also describe the Fri, 29 Aug 2008 18:05:35 GMT http://en.redtram.com/go/149319839/top100/ 6592 | On the Analyticity of Laguerre Series. (arXiv:0808.3926v1 [math.CA]) http://en.redtram.com/go/149319837/top100/ 149319837 The transformation of a Laguerre series $f (z) = \sum_{n=0}^{\infty}\lambda_{n}^{(\alpha)} L_{n}^{(\alpha)} (z)$ to a power series $f (z) =\sum_{n=0}^{\infty} \gamma_{n} z^{n}$ is discussed. Many nonanalytic functionscan be expanded in this way. Thus, success is not guaranteed. Simple sufficientconditions based on Fri, 29 Aug 2008 18:05:35 GMT http://en.redtram.com/go/149319837/top100/ 6592 | Embeddings of C*-surfaces into weighted projective spaces. (arXiv:0808.3877v1 [math.AG]) http://en.redtram.com/go/149319829/top100/ 149319829 Let V be a normal affine surface which admits a C*- and a C+-action. In thisnote we show that in many cases V can be embedded as a principal Zariski opensubset into a hypersurface of a weighted projective space. In Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319829/top100/ 6592 | On a Hamiltonian form of an elliptic spin Ruijsenaars-Schneider system. (arXiv:0808.3875v1 [math-ph]) http://en.redtram.com/go/149319827/top100/ 149319827 An explicit expression of a Hamiltonian form of an elliptic spinRuijsenaars-Schneider is found in the case of 2 particles usingKrichever-Phong's universal symplectic form. In the rational limit it coincideswith a Poisson bracket found by Arutyunov and Frolov. Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319827/top100/ 6592 | O-minimal homotopy and generalized (co)homology. (arXiv:0808.3866v1 [math.LO]) http://en.redtram.com/go/149319826/top100/ 149319826 This article gives a version of the homotopy theory (giving also generalizedhomology and cohomology theories), developed by H. Delfs and M. Knebusch in thesemialgebraic case, extended to regular paracompact locally definable spacesand weakly definable spaces over a model R of Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319826/top100/ 6592 | Higher Rank Wavelets. (arXiv:0808.3879v1 [math.FA]) http://en.redtram.com/go/149319831/top100/ 149319831 A theory of higher rank multiresolution analysis is given in the setting ofabelian multiscalings. This theory enables the construction, from a higher rankMRA, of finite wavelet sets whose multidilations have translates forming anorthonormal basis in $L^2(\bR^d)$. While tensor products of Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319831/top100/ 6592 | A chain morphism for Adams operations on rational algebraic K-theory. (arXiv:0808.3882v1 [math.KT]) http://en.redtram.com/go/149319832/top100/ 149319832 For any regular noetherian scheme X and every k>0, we define a chain morphismbetween two chain complexes whose homology with rational coefficients isisomorphic to the algebraic K-groups of X tensored by the field of rationalnumbers. It is shown that these Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319832/top100/ 6592 | The modular branching rule for affine Hecke algebras of type A. (arXiv:0808.3915v1 [math.RT]) http://en.redtram.com/go/149319835/top100/ 149319835 For the affine Hecke algebra of type A at roots of unity, we make explicitthe correspondence between geometrically constructed simple modules andcombinatorially constructed simple modules and prove the modular branchingrule. The latter generalizes work by Vazirani. Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319835/top100/ 6592 | Quasi-analytische Zerlegungen. (arXiv:0808.3893v1 [math.CV]) http://en.redtram.com/go/149319833/top100/ 149319833 The leaves in singular holomorphic foliation theory are examples ofquasi-analytic layers. In the first part of our publication we are concernedwith a theory of these subjects. A quasi-analytic decomposition of a complexmanifold is a decomposition into pairwise disjoint connected quasi-analyticlayers. Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319833/top100/ 6592 | Parallel in Time Simulation of Multiscale Stochastic Chemical Kinetics. (arXiv:0808.3863v1 [math.NA]) http://en.redtram.com/go/149319824/top100/ 149319824 A version of the time-parallel algorithm parareal is analyzed and applied tostochastic models in chemical kinetics. A fast predictor at the macroscopicscale (evaluated in serial) is available in the form of the usual reaction rateequations. A stochastic simulation algorithm is Fri, 29 Aug 2008 18:05:34 GMT http://en.redtram.com/go/149319824/top100/