Spectral theory (Mathematics) 33 Spectral Theory-- Mathematics 11 Operator theory 6 Linear operators 4 Numerical solutions 3 Congresses 2 Differential equations, Partial 2 Fluid dynamics 2 Functional analysis 2 Gaussian processes 2 Prediction theory 2 Stationary processes 2 Asymptotic expansions 1 Banach algebras 1 Data processing 1 Differential equations, Hyperbolic 1 Differential geometry 1 Differential operators 1 Eigenvalues 1 Elliptic operators 1 Finite element method 1 Finite groups 1 Fourier analysis 1 Geometry, Differential 1 Global analysis (Mathematics) 1 Hamiltonian operator 1 Hilbert space 1 Hypoelliptic operators 1 Inverse problems (Differential equations) 1 Mappings (Mathematics) 1