算子组的拟正常与次正常性

THE QUASINORMAL AND SUBNORMAL nTUPLE OPERATORS

将单个算子的拟正常与次正常的一些结果推广到算子组的情形．证明了重交换拟正常算子组的分解定理；给出了算子组为次正常的充分必要条件；刻划了算子序列的次正常性．

Some results about single quasinormal and subnormal operators are generalized to the situation of ntuples operators.It proves a factorization theorem about ntuples doubly commutative pure quasinormal operators,gives a necessary and sufficient condition for a ntuples operators to be subnormal,and characterizes the subnormality for operator sequences.