局部Jarník-Besicovitch定理的一个简单证明  

A Simple Proof of Localized Jarník-Besicovitch Theorem

作　　者：曹春云[1] 吕凡[1] 

机构地区：[1]华中农业大学理学院,湖北武汉430070

出　　处：《应用数学》2014年第3期467-469,共3页Mathematica Applicata

基　　金：国家自然科学基金(11271114);博士科研启动金(2662013BQ042)

摘　　要：任意的无理数x,其无理指数δx∶=sup{δ≥0∶|x-pq-1|≤q-2δi.o.pq-1}衡量x可以被有理数逼近的程度.经典的Jarník-Besicovitch定理表明,对于任意的δ≥1,集合{x∈R∶δx≥δ}的Hausdorff维数为δ-1.Barral和Seuret[1]考虑该定理的局部化问题,证明对于任意的连续函数f∶R→[1,+∞),集合{x∈R∶δx≥f(x)}的Hausdorff维数为(inf{f(x)∶x∈R})-1.本文从经典的Jarník-Besicovitch定理出发,利用连分数的理论给出局部Jarník-Besicovitch定理一个简短的证明.For any irrational number x,the irrational exponentδx∶=sup{δ≥0∶｜xpq-1｜≤q-2δi.o.pq-1}plays an important role in Diophantine approximation.The classic Jarník-Besicovitch theorem shows that for anyδ≥1,the Hausdorff dimension of the set{x∈R∶δx ≥δ}equalsδ-1.The localization of this theorem is considered by Barral and Seuret[1].They proved that for any continuous function f∶R→[1,＋∞）,the Hausdorff dimension of the set{x∈R∶δx ≥f（x）}is（inf{f（x）∶x∈ R}）-1.In this paper,we give a short proof of the localized Jarník-Besicovitch theorem by continued fraction.

关 键 词：局部Jarník-Besicovitch定理 连分数 丢番图逼近 

分 类 号：O156[理学—数学]