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论文类型：期刊论文

发表时间：2009-09-01

发表刊物：INTEGRAL EQUATIONS AND OPERATOR THEORY

收录刊物：SCIE、Scopus

卷号：65

期号：1

页面范围：115-129

ISSN号：0378-620X

关键字：Hyponormality; weighted Bergman space; Hankel operator; Toeplitz operator

摘要：Consider phi - f + (g) over bar, where f and g are polynomials, and let T(phi) be the Toeplitz operators with the symbol phi. It is known that if T(phi) is hyponormal then vertical bar f'(z)broken vertical bar(2) >= vertical bar g'(z)vertical bar(2) on the unit circle in the complex plane. In this paper, we show that it is also a necessary and sufficient condition under certain assumptions. Furthermore, we present some necessary conditions for the hyponormality of T(phi) on the weighted Bergman space, which generalize the results of I. S. Hwang and J. Lee.