Approximation by semi-Fredholm operators with fixed nullity
The author determines the distance from a bounded linear operator on a Hilbert space to semi-Fredholm operators with fixed nullity. As a consequence of his results he obtains the somewhat surprising fact that the closure of the union of the right semi-Fredholm operators and the left semi-Fredholm operators equals the algebra of all continuous endomorphisms.
distance from a bounded linear operator on a Hilbert space to semi- Fredholm operators with fixed nullity
the closure of the union of the right semi-Fredholm operators and the left semi-Fredholm operators equals the algebra of all continuous endomorphisms
scientific article; zbMATH DE number 4200971