COMPACT DIFFERENCES OF COMPOSITION OPERATORS ON HOLOMORPHIC FUNCTION SPACES IN THE UNIT BALL

摘要

We find a lower bound for the essential norm of the difference of two composition operators acting on H2(BN) or A28(BN) (s ＞ -1).This result plays an important role in proving a necessary and sufficient condition for the difference of linear fractional composition operators to be compact,which answers a question posed by MacCluer and Weir in 2005.