简介:Inthispaper,weproposeadimension-reducing,K-meanclusteringprocedurebyProjectionPursuit(PP)techniquesoastoexploretheclusteringstructureofdatainhigh-dimensionalspaceintermsoflow-dimensionalprojectivepointsofdata,andweobtainthea.s.consistenceoftheestimatesoftheclustercentersandprojectionorientations.
简介:在这篇论文,我们为多项式建立L~q不平等,它特别地产出一些Zygmund类型不平等的有趣的归纳。
简介:Inordertogiveacompleteandaccuratedescriptionaboutthesensitivityofefficientportfoliostochangesinassets'expectedreturns,variancesandcovariances,thejointeffectofestimationerrorsinmeans,variancesandcovariancesontheefficientportfolio'sweightsisinvestigatedinthispaper.Itisprovedthattheefficientportfolio'scompositionisaLipschitzcontinuous,differentiablemappingoftheseparametersundersuitableconditions.Thechangerateoftheefficientportfolio'sweightswithrespecttovariationsaboutriskreturnestimationsisderivedbyestimatingtheLipschitzconstant.Ourgeneralquantitativeresultsshowthattheefficientportfolio''sweightsarenormallynotsosensitivetoestimationerrorsaboutmeansandvariances.Moreover,wepointoutthoseextremecaseswhichmightcausestabilityproblemsandhowtoavoidtheminpractice.Preliminarynumericalresultsarealsoprovidedasanillustrationtoourtheoreticalresults.
简介:在这篇论文,我们在联合起来的磁盘D上学习Hakopian插值的加权的吝啬的不可分的集中。我们出现在Hakopian插值多项式Hn之间的内部产品(f;x,y);光滑的功能g(x,y)在D上收敛到f的(x,y);g(x,y)在D上什么时候n→8f(x,y)属于C(D);g的所有第一部分衍生物(x,y)属于空间嘴唇M[α](0<α≤1)。我们进一步证明那提供了g的所有秒部分的衍生物(x,y)也属于空间嘴唇M[α];f(x,y)属于C[1](D),在Hakopian插值的部分衍生物之间的内部产品多项式;g(x,y)在D上收敛到那在之间;g(x,y)在D上什么时候n→∞。
简介:Somediseasesotherthancardiacdiseasecanbe“prevented”,butthepurposeofthiscommunicationwrittenbyaclinicalcardiologist,notasapreventionspecialist,istofocusstrictlyoncardiovasculardisease.Thedefinitionofpreventivemedicineinsimplesttermsmeanskeepingyourpatienthealthy.Inadditiontomaintaininghealth,ofcourse,wewanttopreventthedisabilityassociatedwithcardiacdiseaseaswellasdeathintheyoungerperson.
简介:TheDeGrootmodelisoneofthemostclassicalmodelsinthefieldofopiniondynamics.ThestandardDeGrootmodelassumesthatagentsarehomogeneousandupdatetheiropinionsinthedirectionofaweightedaverageoftheirneighbors'opinions.Onenaturalquestioniswhetherasecondtypeofagentscouldsignificantlychangethemainpropertiesofthemodel.Theauthorsaddressthisquestionbyintroducingrebels,whoupdatetheiropinionstowardtheoppositeoftheirneighbors'weightedaverage.Theauthorsfindthattheexistenceofrebelsremarkablyaffectstheopiniondynamics.Undercertainmildconditions,theexistenceofafewrebelswillleadthegroupopiniontothegoldenmean,regardlessoftheinitialopinionsoftheagentsandthestructureofthelearningnetwork.ThisresultiscompletelydifferentfromthatofthestandardDeGrootmodel,wherethefinalconsensusopinionisdeterminedbyboththeinitialopinionsandthelearningtopology.Thestudythenprovidesnewinsightsintounderstandinghowheterogeneousindividualsinagroupreachconsensusandwhythegoldenmeanissocommoninhumansociety.
简介:Theweightedarithmeticalmeancomplexjudgementmatrix(WAMCJM)isthemostcommonmethodforaggregatinggroupopinions,butithasashortcoming,namelytheWAMCJMoftheperfectlyconsistentjudgementmatricesgivenbyexpertscanotguaranteeitsperfectconsistency.AnupperboundoftheWAMCJM'sconsistencyispresented.Simultaneously,acompatibilityindexofjudgingtheaggregatingextentofgroupopinionsisalsointroduced.TheWAMCJMisofacceptableconsistencyandisprovedprovidedthecompatibilitiesofalljudgementmatricesgivenbyexpertsaresmallerthanthethresholdvalueofacceptableconsistency.Theseconclusionsareimportanttogroupdecisionmaking.
简介:Inthispaper,westudytheasymptoticCUSUMtestsfordetectingchangesinthemeanorvarianceofamoving-averageprocesswithlongmemory.Whenthereisnochangeover[O,T],theasymptoticdistributionoftheteststatisticisderived,whichallowsustofindasymptoticcriticalvalues.Whenthereisachange,thebehavioroftheteststatisticisdiscussed.Conditionsfortheconsistencyofthesetestsarealsodiscussed.Basedontheasymptoticresults,simulationstudiesoftestingforchangesinthemeanshowthattheCUSUMtestproposedperformswell.