Hilbert space Operator theory 8 Banach spaces 3 Functional analysis 3 Spectral theory (Mathematics) 3 Calculus of variations 2 Congresses 2 Convex functions 2 Convex programming 2 Linear operators 2 Measure theory 2 Banach algebras 1 Boundary value problems 1 C*-algebras 1 Differential equations 1 Differential equations, Partial 1 Electric networks 1 Functions 1 Functions, Entire 1 Generalized spaces 1 Harmonic analysis 1 Homeomorphisms 1 Ideals (Algebra) 1 Integrals, Generalized 1 Invariant subspaces 1 Lattice theory 1 Linear topological spaces 1 Manifolds (Mathematics) 1 Mathematical optimization 1 Mathematical physics 1