4.II.22G

Linear Analysis
Part II, 2006

Let HH be a complex Hilbert space. Define what it means for a linear operator T:HHT: H \rightarrow H to be self-adjoint. State a version of the spectral theorem for compact selfadjoint operators on a Hilbert space. Give an example of a Hilbert space HH and a compact self-adjoint operator on HH with infinite dimensional range. Define the notions spectrum, point spectrum, and resolvent set, and describe these in the case of the operator you wrote down. Justify your answers.