简介:ThisarticleconsidersweightedapproximationofmultivariatefunctioninreproducingkernelHilbertspace,andgivesarelationbetweennthminimalerrorsforstandardandlinearinformationintherandomizedsetting.Usingthisrelationwecanestimatethenthminimalerrorforstandardinformationbythenthminimalerrorforlinearinformation,andstudythetractabilityandstrongtractabilityforthesetwoclassesofinformation.
简介:Theauthorsdefinethesceneryflowofthetorus.Theflowspaceistheunionofallflat2-dimensionaltoriofarea1withamarkeddirection(orequivalently,theunionofalltoriwithaquadraticdifferentialofnorm1).Thisisa5-dimensionalspace,andtheflowactsbyfollowingindividualpointsunderanextremaldeformationofthequadraticdifferential.Theauthorsdefineassociatedhorocycleandtranslationflows;thelatterpreserveeachtorusandarethehorizontalandverticalflowsofthecorrespondingquadraticdifferential.Thesceneryflowprojectstothegeodesicflowonthemodularsurface,andadmits,foreachorientationpreservinghyperbolictoralautomorphism,aninvariant3-dimensionalsubsetonwhichitisthesuspensionflowofthatmap.Theauthorsfirstgiveasimplealgebraicdefinitionintermsofthegroupofaffinemapsoftheplane,andprovethattheflowisAnosov.Theygiveanexplicitformulaforthefirst-returnmapoftheflowonconvenientcross-sections.Then,inthemainpartofthepaper,theauthorsgiveseveraldifferentmodelsfortheflowanditscross-sections,intermsof:●stackingandrescalingperiodictilingsoftheplane;●symbolicdynamics:thenaturalextensionoftherecodingofSturmiansequences,ortheS-adicsystemgeneratedbytwosubstitutions;●zoomingandsubdividingquasi-periodictilingsoftherealline,oraperiodicquasicrystalsofminimalcomplexity;●thenaturalextensionoftwo-dimensionalcontinuedfractions;●inductiononexchangesofthreeintervals;●rescalingonpairsoftransversemeasurefoliationsonthetorus,ortheTeichmiillerflowonthetwice-puncturedtorus.
简介:WeshowthatmanyharmonicanalysisoperatorsintheBesselsetting,includingmaximaloperators,Littlewood–Paley–Steintypesquarefunctions,multipliersofLaplaceorLaplace–StieltjestransformtypeandRiesztransformsare,orcanbeviewedas,Calderón–Zygmundoperatorsforallpossiblevaluesoftypeparameterλinthiscontext.Thisextendsresultsexistingintheliterature,butbeingjustifiedonlyforarestrictedrangeofλ.
简介:Inthispaper,westudyoptimalrecovery(reconstruction)offunctionsonthesphereintheaveragecasesetting.WeobtaintheasymptoticordersofaveragesamplingnumbersofaSobolevspaceonthespherewithaGaussianmeasureintheLd-1q(S)metricfor1≤q≤∞,andshowthatsomeworst-caseasymptoticallyoptimalalgorithmsarealsoasymptoticallyoptimalintheaveragecasesettingintheLdq(S-1)metricfor1≤q≤∞.
简介:ManyworkshaveinvestigatedtheproblemofreparameterizingrationalBéziercurvesorsurfacesviaMbiustransformationtoadjusttheirparametricdistributionaswellasweights,suchthatthemaximalratioofweightsbecomessmallerthatsomealgebraicandcomputationalpropertiesofthecurvesorsurfacescanbeimprovedinaway.However,itisanindicationofveracityandoptimizationofthereparameterizationtodopriortojudgewhetherthemaximalratioofweightsreachesminimum,andverifythenewweightsafterMbiustransformation.What’smoretheusersofcomputeraideddesignsoftwaresmayrequiresomeguidelinesfordesigningrationalBéziercurvesorsurfaceswiththesmallestratioofweights.Inthispaperwepresentthenecessaryandsufficientconditionsthatthemaximalratioofweightsofthecurvesorsurfacesreachesminimumandalsodescribeitbyusingweightssuccinctlyandstraightway.Theweightsbeingsatisfiedtheseconditionsarecalledbeinginthestablestate.Applyingsuchconditions,anygivingrationalBéziercurveorsurfacecanautomaticallybeadjustedtocomeintothestablestatebyCADsystem,thatis,thecurveorsurfacepossessesitsoptimalparametricdistribution.Finally,wegivesomenumericalexamplesfordemonstratingourresultsinimportantapplicationsofjudgingthestablestateofweightsofthecurvesorsurfacesanddesigningrationalBéziersurfaceswithcompactderivativebounds.
简介:在这篇论文,我们在不同计算设定在n宽度上从空格l_p(1≤p≤2)为斜操作符T把一些最佳的算法给l_2。