The authors express the essential norms of composition operators between Hardy spaces of the unit disc in terms of the natural Nevanlinna counting function.
基金Project supported by the National Natural Science Foundation of China (No. 10771201)the Anhui Provincial Natural Science Foundation of China (No. 090416233)
文摘The authors express the essential norms of composition operators between Hardy spaces of the unit disc in terms of the natural Nevanlinna counting function.