A simple proof of the Fredholm alternative and a characterization of the Fredholm operators
| dc.creator | Ramm, A. G. | |
| dc.date | 2000-11-17 | |
| dc.date.accessioned | 2026-07-07T04:38:40Z | |
| dc.date.available | 2026-07-07T04:38:40Z | |
| dc.description | Let $A$ be a linear bounded operator in a Hilbert space $H$, $N(A)$ and $R(A)$ its null-space and range, and $A^*$ its adjoint. The operator $A$ is called Fredholm iff $dim N(A)= dim N(A^*):=n<\infty$ and $R(A)$ and $R(A^*)$ are closed subspaces of $H$. A simple and short proof is given of the following known result: $A$ is Fredholm iff $A=B+F$, where $B$ is an isomorphism and $F$ is a finite-rank operator. The proof consists in reduction to a finite-dimensional linear algebraic system which is equivalent to the equation $Au=f$ in the case of Fredholm operators. | |
| dc.description | 6pp, a selfcontained, short and simple proof of the Freholm alternative and of a characterization of Fredholm operators. The paper is written for broad audience. It is of expository nature and does not contain new results | |
| dc.identifier | https://arxiv.org/abs/math/0011133 | |
| dc.identifier | http://arxiv.org/abs/math/0011133 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/60373 | |
| dc.subject | Functional Analysis | |
| dc.subject | Spectral Theory | |
| dc.subject | 45B05, 47A53 | |
| dc.title | A simple proof of the Fredholm alternative and a characterization of the Fredholm operators | |
| dc.type | text |