کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4602352 | 1631167 | 2008 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Which 2-hyponormal 2-variable weighted shifts are subnormal?
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موضوعات مرتبط
مهندسی و علوم پایه
ریاضیات
اعداد جبر و تئوری
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چکیده انگلیسی
It is well known that a 2-hyponormal unilateral weighted shift with two equal weights must be flat, and therefore subnormal. By contrast, a 2-hyponormal 2-variable weighted shift which is both horizontally flat and vertically flat need not be subnormal. In this paper we identify a large class S of flat 2-variable weighted shifts for which 2-hyponormality is equivalent to subnormality. One measure of the size of S is given by the fact that within S there are hyponormal shifts which are not subnormal.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Linear Algebra and its Applications - Volume 429, Issues 8–9, 16 October 2008, Pages 2227-2238
Journal: Linear Algebra and its Applications - Volume 429, Issues 8–9, 16 October 2008, Pages 2227-2238