Operator theory 21 Hilbert space 8 Functional analysis 3 Congresses 2 Harmonic analysis 2 Interpolation 2 Linear systems 2 Numerical solutions 2 System analysis 2 Banach algebras 1 Cauchy problem 1 Data processing 1 Differential equations 1 Equations 1 Ideals (Algebra) 1 Integral equations 1 Invariant subspaces 1 Inverse problems (Differential equations) 1 Kernel functions 1 Least squares 1 Linear operators 1 Markov processes 1 Mathematical physics 1 Operator algebras 1 Regression analysis 1 Scattering (Mathematics) 1 Signal processing 1 Singular integrals 1 Statistics 1