Expanding on questions traditionally treated as the core of Hilbert space theory, this book focuses on unbounded operators, develops spectral theory for a finite family of commuting self-adjoint operators and describes the unitary invariants of such families.

Expanding on questions traditionally treated as the core of Hilbert space theory, this book focuses on unbounded operators, develops spectral theory for a finite family of commuting self-adjoint operators and describes the unitary invariants of such families.