Toeplitz operators and mean winding numbers
نویسنده
چکیده
For a continuous nonvanishing complex-valued function g on the real line, several notions of a mean winding number are introduced. We give necessary conditions for a Toeplitz operator with matrixvalued symbol G to be semi-Fredholm in terms of mean winding numbers of detG. The matrix function G is assumed to be continuous on the real line, and no other apriori assumptions on it are made. AMS Subject classification: 47B35 (47A53 47G30)
منابع مشابه
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