关于零对合类算子

本文定义了ＮＩ算子和ＡＮＩ算子，给出共轭算子下有界时，一个算子为ＮＩ类算子的等价条件，并在一定条件下证明了ＮＩ类算子具有闭的数值值域．最后，本文研究了ＮＩ类算子对，尤其是Ｈ２空间上的Ｔｏｅｐｌｉｔｚ算子对，刻划了Ｔ＝（Ｔφ，Ｔ＊φ）的联合谱

On Null Involutary Operators

We start from the equality ker T 2 =ker T to define a NI operator and an ANI Operater, then display some of their elementary properties. When T * is bounded from below, we give an equivalent condition for T to be a NI operator. Under some conditions, we proved that the numerical ranges of a NI operator is closed. We also study the pair case, especially the pairs of Toeplitz operators, and we characterize the jointed spectrum of the NI pair T=(T φ,T * φ ).