Operator theory 45 Mathematics 39 Differential equations, Partial 15 Functional analysis 14 Functions of complex variables 10 Integral equations 6 Systems theory 6 Matrix theory 4 Numerical analysis 4 Boundary value problems 3 Differential equations 3 Harmonic analysis 3 Topological groups 3 Algebra 2 Differentiable dynamical systems 2 Differential operators 2 Distribution (Probability theory) 2 Functional equations 2 Mathematical physics 2 Partial differential equations 2 Spectral theory (Mathematics) 2 Toeplitz operators 2 Banach spaces 1 Calculus 1 Clifford algebras 1 Combinatorics 1 Computer science 1 Difference equations 1 Differential equations, Hyperbolic 1 Differential geometry 1