摘 要: | In this paper, for notation and terminology, we follow the article1]. 1.The twenty-seventh question of Allen Shields1] asks: if T is an injective bilateral shift, must T or T have a cyclic vector ? we now answer this question for a class of injective bilateral weighted shifts. Theorem 1. Let T be an injective bilateral weighted shift. If T is hyponormal but nonnormal , then T~* has no cyclic vectors, and T has a cyclic vector.
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