PHANTOM MAPS AND SPACES OF THE SAME n-TYPE FOR ALL n

1.IntroductionLetXbeaconnectedCWcomplexandX.denoteitsn-skeleton.Amapf:X-YiscalledaphantommapifitsrestrictiontoeachskeletonXuisnullhomotopic.ItiseasytoknowthateveryphantommapfromafiniteCWcomplexortoaspacewithonlyfinitenootrivialhomotopygroupsisnecessarilytrivialuptohomotopy.HenceessentialphantommapcanoccuronlywhenthedomainXisaninfinitedimensionalspaceorthetargetisaspacewithinfinitenontrivialhomotopygroups.Suchmapsappeartobenullhomotopicfromanumberofdifferentpoilltsofview;e.g.,theyinducethe…     

POLES OF ZETA FUNCTIONS OF COMPLETE INTERSECTIONS

51.IntroductionLetF.beafinitefieldofqele~swithcharederisticp.LetXbeanThdilnensionalalgebraicsetdeadedoverF..ThezetafunctionofX/F.isdennedbywhereXOdenotesthesetofclosedpointsOfX/F.and#X(F.d)denotesthenUInberof.F.d-rationalpointsonX.ItiseasytoseethatZ(X,T)isapowerserieswithintegercoefficients.Dwork'srationalltytheoremIg]showsthatthezetafunctionZ(X,T)isrationalinT.ThuS,therearealgebraicintegerspll'.3Pr,pl,'3basuchthatThereisagoodreasonthatwemoantheabovezetafunctionbythepower(--1)"-…     

TWO-DIMENSIONAL RIEMANN PROBLEMS： FROM SCALAR CONSERVATION LAWS TO COMPRESSIBLE EULER EQUATIONS

In this paper we survey the authors＇ and related work on two-dimensional Riemann problems for hyperbolic conservation laws, mainly those related to the compressible Euler equations in gas dynamics. It contains four sections： 1. Historical review. 2. Scalar conservation laws. 3. Euler equations. 4. Simplified models.     

Improvement of convergence to steady state solutions of Euler equations with weighted compact nonlinear schemes

The convergence to steady state solutions of the Euler equations for weighted compact nonlinear schemes (WCNS) [Deng X. and Zhang H. (2000), J. Comput. Phys. 165, 22-44 and Zhang S., Jiang S. and Shu C.-W. (2008), J. Comput. Phys. 227, 7294-7321] is studied through numerical tests. Like most other shock capturing schemes, WCNS also suffers from the problem that the residue can not settle down to machine zero for the computation of the steady state solution which contains shock waves but hangs at the truncation error level. In this paper, the techniques studied in [Zhang S. and Shu. C.-W. (2007), J. Sci. Comput. 31, 273-305 and Zhang S., Jiang S and Shu. C.-W. (2011), J. Sci. Comput. 47, 216-238], to improve the convergence to steady state solutions for WENO schemes, are generalized to the WCNS. Detailed numerical studies in one and two dimensional cases are performed. Numerical tests demonstrate the effectiveness of these techniques when applied to WCNS. The residue of various order WCNS can settle down to machine zero for typical cases while the small post-shock oscillations can be removed.     

D.C.隶属函数模糊集及其应用(I)--D.C.隶属函数模糊集基本概念与性质

本文是D.C.隶属函数模糊集及其应用系列研究的第一部分.建立了D.C.隶属函数模糊集的基本概念.探讨了D.C.隶属函数模糊集的基本性质和D.C.隶属函数模糊集对一些常见的重要t模、余模和伪补的封闭性.并以此建立了丰富的模糊数学应用模型.     

CONTINUOUS L-DOMAINS

61.IntroductionConiinuousDCPOisoneofthemostimportantstructuresin-domaintheory.Unfor-tunatelythecategoryofcolltinuousDCPOandtheScottcontinuousfunctionsfailstobeCartesianclosed,soitisaverysignificantproblemtofinditsmakimalCartesianclosedfullsubcategories.ThecategoryofL-domain'swasdiscoveredbyA.JungwhilesolvingtheproblemoffindingmtalmalCartesianclosedcategoriesofalgebraicDCPO's[1l,andrecentworksbyA.JungandG.Gund.r[2]showsthatthecategoryofL-domain'sisaninterestingcategoryOntheotherhand,i…     

CONVERGENCE RATE OFDISTRIBUTIONS OF TRIMMED SUMS

1.IntroductionLet{Xn,n2l}beasequenceofi.i.d.randomvariableswithnondegeneratedistributionF.Fornonnegativeintegersk.andrn,k. rn相似文献   

本刊英文版Vol.28(2012),No.8论文摘要(英文)

<正>Estimating Complex Covariance by Observing Two Variables at a Time C.S.WITHERS S.NADARAJAH O.NφRKLI R.RAICH R.G.VAUGHAN     

A THEOREM ON PLURICANONICAL MAPS OF NONSINGULAR MINIMAL THREEFOLDS OF GENERAL TYPE

51.IntroductionandtheMainTheoremLetXbeacomplexnonsingularminimalprojectivethreefoldofgeneraltype.ThenatureofpluricanonicalmapsofXisveryimportanttotheclassificationtheory.Itiswell-knownfrom[10]that4linK.lisabirationalmapform27.In[3],itisprovedthat6-canonicalmapofXisabirationalmapontoitsimage.Inthispaper,wemainlystudythefollowingproblem:Problem.WhatisthegreatestpositiveintegercosuchthatImoKxliscomposedOjapencilOjsudecesforsomeX,i.e.,dim4Im.H.I(X)=1?Benv.ni,te[1]provedthatmo53.Wecaneasily…     

Fibrations and stability for compact group actions on manifolds with local bounded Ricci covering geometry

In the study of the collapsed manifolds with bounded sectional curvature,the following two results provide basic tools:a(singular)fibration theorem by K.Fukaya[J.Differential Gcom.,1987.25(1):139156]and J.Cheeger,K.Fukaya,and M.Gromov[J.Airier.Math.Soc.,1992.5(2):327372],and the stability for isometric compact Lie group actions on manifolds by R.S.Palais[Bull.Amer.Math.Soc.,1961,67(4):362364]and K.Grove and H.Karcher[Math.Z..1973,132:1120].The main results in this paper(partially)generalize the two results to manifolds with local bounded Ricci covering geometry.