Perturbing Fredholm operators to obtain invertible operators |
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Authors: | Harold Widom |
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Institution: | Division of Natural Sciences, University of California, Santa Cruz, California 95060 U.S.A. |
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Abstract: | A condition is given on a set of operators on Hilbert space that guarantees it has the following property: For any Fredholm operator T of index zero there exists anA? such that T + ?A is invertible for all sufficiently small nonzero ?. As a corollary one obtains in a quite general setting the density of the invertible Toeplitz operators in the set of Fredholm Toeplitz operators of index zero. |
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