简介:摘 要:在各种多维数据查询技术中,索引结构对数据的存储及查询处理起关键作用。但常用的索引,如R树以及其变体主要集中对数据空间或数据对象进行分区,可能会导致存储消耗大且查询时间较长。相较于传统索引,学习型索引通过学习数据的分布与特征,进而可优化索引结构,提高查询效率并减少索引所占用的存储空间。因此本文设计了一种新的多维索引结构HM-索引,其主要分为两个阶段:第一阶段使用Hilbert曲线将多维数据映射成一维的方式存储;第二阶段使用学习型索引模型学习映射后数据的分布。本文主要实现了点查询、范围查询,验证表明本文所提出的索引方法明显优于R树以及其他代替方案。
简介:TheauthorsdefinethedirectionalhyperHilberttransformandgiveitsmixednormestimate.Thesimilarconclusionsforthedirectionalfractionalintegralofonedimensionarealsoobtainedinthispaper.Asanapplicationoftheaboveresults,theauthorsgivetheLp-boundednessforaclassofthehypersingularintegralsandthefractionalintegralswithvariablekernel.Moreover,asanotherapplicationoftheaboveresults,theauthorsprovethedimensionfreeestimateforthehyperRiesztransform.ThisisanextensionoftherelatedresultobtainedbyStein.
简介:LetS∞denotetheunitsphereinsomeinfinitedimensionalcomplexHilbertspace(H,<·,·>)Letz1,z2,…,z1bedistinctpointsonS∞Thispaperdealswithinterpolationofarbitrarydataonthezjbyafunctioninthelinearspanofthelfunctionswhenisasuitablefunctionthatoperatesonnonnegativedefinitematrices.Conditionsforthestrictpositivedefinitenessofthekernelareobtained.
简介:In[1-5],itwasinvestigaedtherealizationsofweightingpatternsinHilbertspaces.Thisnotedealswithdiscretesystemswhichhaveoperatorweightingpartterns.Theorems2-4arenecessaryandsufficientconditionsforJ-unitaryrealizationandforJ-selfadjoint
简介:获得了HilbertC^*-模之间的两个同构定理.作为推论,证明了C^*-代数上每个可数生成的HilbertC^*-模均稳定酉等价于A。
简介:Inthispaper,twoalgorithmsarepresentedforgeneratingtwocodescanlistsofanN-dimensionalHilbertcell,andaformalproofofthebackwardencodingalgorithmisgiven.Onthebasisoftheself-simi-laritypropertiesofaHilbertcurve,thispapergivesanovelalgorithmforgeneratingastaticevolvementruletablethroughanalyzingaHilbertcell.Bylookingupthestaticevolvementruletable,theN-dimensionalHilbertmappingsareefficientlyimplemented.
简介:Considerthepositived-dimensionallatticed+(d≥2)withpartialordering≤,let{XK;K∈d+}bei.i.d.randomvari-ablestakingvaluesinarealseparableHilbertspace(H,||·||)withmeanzeroandcovarianceoperator∑,andsetpartialsumsSN=∑K≤NXK,K,N∈d+.Undersomemomentconditions,weobtainthepreciseasymptoticsofakindofweightedinfiniteseriesforpartialsumsSNasε0byusingthetruncationandapproximationmethods.TheresultsarerelatedtotheconvergenceratesofthelawofthelogarithminHilbertspace,andtheyalsoextendtheresultsof(GutandSpǎtaru,2003).
简介:本文给出了Hibert空间中正交基扰动的一个结果及一个实例。
简介:Westudythenormretrievalbyprojectionsonaninfinite-dimensionalHilbertspaceH.Let{e_i}_(i∈I)beanorthonormalbasisinHandW_i={e_i}~⊥foralli∈I.Weshowthat{W_i}_(i∈I)doesnormretrievalifandonlyifIisaninfinitesubsetofN.Wealsogivesomepropertiesofnormretrievalbyprojections.
简介:ThemainobjectiveofthisworkistodecomposeorthogonallythereproducingkernelsHilbertspaceusinganyconditionallypositivedefinitekernelsintosmalleronesbyintroducingthetheoryofpowerkernels,andtoshowhowtodothisdecompositionrecursively.Itmaybeusedtosplitlargeinterpolationproblemsintosmalleroneswithdifferentkernelswhicharerelatedtotheoriginalkernels.Toreachthisobjective,wewillreconstructthereproducingkernelsHilbertspaceforthenormalizedandtheextendedkernelsandgivetherecursivealgorithmofthisdecomposition.
简介:Inthispaper,wefirstdeterminetherelationsamongthebestboundsAandBoftheg-frame,theg-frameoperatorSandthepre-frameoperatorQandgiveanecessaryandsufficientconditionforag-framewithboundsAandBinacomplexHilbertspace.Wealsointroducethedefinitionofag-framesequenceandobtainanecessaryandsufficientconditionforag-framesequencewithboundsAandBinacomplexHilbertspace.Lastly,weconsiderthestabilityofag-framesequenceforacomplexHilbertspaceunderperturbation.
简介:在N-解析函数类中,对于无穷直线上的Riemann-Hilbert边值问题,通过轴的对称扩张法将其转化为在附加条件下相应的Riemann边值问题,从而建立了其齐次和非齐次问题的可解性理论。