THE ESSENTIAL NORMALITY OF Nη-TYPE QUOTIENT MODULE OF HARDY MODULE ON THE POLYDISC
THE ESSENTIAL NORMALITY OF Nη-TYPE QUOTIENT MODULE OF HARDY MODULE ON THE POLYDISC
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发表时间:
2013
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通讯作者:
Penghui Wang
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作者:
Penghui Wang
The purpose of this note is to study the essential normality of Nηtype quotient modules, generated by {ηi(zi) − ηi+1(zi+1) | i = 1, · · · , n − 1}, of the Hardy module over the polydisc for inner functions ηi. In 1988, Clark studied the structure of Nη , for which ηi are finite Blaschke products, and as a consequence, Nη is essentially normal if ηi are finite Blaschke products. In this note, we will prove that to obtain the essential normality of Nη , the condition that ηi are finite Blaschke products is necessary.