Unbounded Self-Adjoint Operators on Hilbert Space

This textbook provides a modern account of the theory of unbounded self‑adjoint operators on Hilbert spaces and their spectral theory, with emphasis on applications in mathematical physics (Schrödinger operators) and analysis (Dirichlet and Neumann Laplacians, Sturm–Liouville operators, and the Hamburger moment problem). The new edition has been thoroughly revised and updated and features an extensive treatment of the self‑adjoint extension theory of symmetric operators. In addition, a numb...