DOUBLE Φ-INEQUALITIES FOR BANACH-SPACE-VALUED MARTINGALES  

作　　者：王迎占 张超 侯友良 

机构地区：[1]School of Mathematics and Statistics,Wuhan University,Wuhan 430072,China [2]College of Mathematics and Information Sciences,Guangzhou University,Guangzhou 510006,China

出　　处：《Acta Mathematica Scientia》2012年第4期1627-1636,共10页数学物理学报（B辑英文版）

基　　金：supported by the National Natural Science Foundation of China (11071190)

摘　　要：Let B be a Banach space, φ1, φ2 be two generalized convex φ-functions and φ1, φ2 the Young complementary functions of ψ1, ψ2 respectively with∫t t0ψ2（s）/sds≤ds≤c0ψ1（c0t）（t〉t0）for some constants co 〉 0 and to 〉 0, where ψ1 and ψ2 are the left-continuous derivative functions of ψ1 and ψ2, respectively. We claim that： （i） If B is isomorphic to a p-uniformly smooth space （or q-uniformly convex space, respectively）, then there exists a constant c 〉 0 such that for any B-valued martingale f = （fn）n≥0,｜｜f^＊｜｜φ1≤｜｜S^（p）（f）｜｜φ2（of｜｜S^（q）（f）｜｜φ1≤c｜｜f^＊｜｜φ2,respectively）,where f^＊ and S^（p） （f） are the maximal function and the p-variation function of f respectively; （ii） If B is a UMD space, Tvf is the martingale transform of f with respect to v = （Vn）z≥0 （V^＊ 〈 1）, then ｜｜（Tvf）^＊｜｜Ф1≤f^＊｜｜Ф2.Let B be a Banach space, φ1, φ2 be two generalized convex φ-functions and φ1, φ2 the Young complementary functions of ψ1, ψ2 respectively with∫t t0ψ2（s）/sds≤ds≤c0ψ1（c0t）（t〉t0）for some constants co 〉 0 and to 〉 0, where ψ1 and ψ2 are the left-continuous derivative functions of ψ1 and ψ2, respectively. We claim that： （i） If B is isomorphic to a p-uniformly smooth space （or q-uniformly convex space, respectively）, then there exists a constant c 〉 0 such that for any B-valued martingale f = （fn）n≥0,｜｜f^＊｜｜φ1≤｜｜S^（p）（f）｜｜φ2（of｜｜S^（q）（f）｜｜φ1≤c｜｜f^＊｜｜φ2,respectively）,where f^＊ and S^（p） （f） are the maximal function and the p-variation function of f respectively; （ii） If B is a UMD space, Tvf is the martingale transform of f with respect to v = （Vn）z≥0 （V^＊ 〈 1）, then ｜｜（Tvf）^＊｜｜Ф1≤f^＊｜｜Ф2.

关 键 词：MARTINGALE convex O-inequality martingale transform weighted average 

分 类 号：O177.2[理学—数学] O211.6[理学—基础数学]