在Cd中,由函数g(z)= ∑n=0∞anzn(an≥0)生成的解析Hilbert空间Hdg(Bd√R)是酉不变的再生核Hilbert空间. 本文证明了,当d≥ 2时,若sup{anRn}<+∞,则有球代数A(Bd√R)中的函数f∉M,即Hdg(Bd√R)上的乘子代数M是H∞(Bd√R)的真子集. 由此可知,若存在M > 0,使得0 ≤ a0 ≤ a1 ≤ … ≤ M,n = 0,1,2,…,则Hdg(Bd√R)不是次正规的.因而不存在Cd中的正测度μ,使得对任何f ∈Hdg(Bd√R)||f||Hdg2 = ∫Cd |f|(z)|2dμ(z),而且在Hdg(Bd√R)上的von Neumann不等式不成立.
Abstract
Let Bd be the unit ball ofd-dimensional complex Euclid space Cd, Hdg (Bd√R) the reproducing kernel Hilbert space with U-invariant reproducing kernel K(z,w) = g(<z,w>), where g(z) = ∑n=0∞ anzn (an ≥ 0) is the generating function of the space Hdg (Bd√R). In this paper, we show that the multiplier algebra of the space Hdg (Bd√R) is a proper subset of H∞(Bd√R), and there exists a holomorphic self-mapping ø from Bd√Rinto Bd√Rsuch that the multiplication operator Møis not bounded when the sequence {an}n∞=0 is bounded andd ≥ 2. Furthermore, we prove that if the coefficients sequence {an}n∞=0 of the generating function g is a bounded, non-decreasing sequence, i.e. there exists a positive number M such that 0 ≤ a0 ≤ a1 ≤ … ≤ M, n = 0, 1, 2, …, then the space Hdg (Bd√R) is not subnormal, in other words, there is not any positive measure μ on Cd such that ||f|| Hdg2 =∫ Cd |f(z)|2dμ(z), for each f∈Hdg (Bd√R), and then von Neumann's inequality does not hold on the space Hdg (Bd√R).
关键词
再生核Hilbert空间 /
复合算子 /
乘子 /
次正规性 /
von Neumann不等式
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Key words
reproducing kernel Hilbert space /
multiplier /
composition operator /
subnormality /
von Neumann's inequality
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参考文献
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脚注
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基金
浙江省自然科学基金资助项目(Y6110824);浙江省重点学科“基础数学”建设经费资助项目
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