Operator theory Mathematics 87 Functional analysis 41 Differential equations, Partial 23 Functions of complex variables 18 Mathematical optimization 16 Differential equations 11 Mathematical physics 11 Distribution (Probability theory) 9 Global analysis (Mathematics) 9 Numerical analysis 9 Harmonic analysis 8 Systems theory 8 Topological groups 7 Integral equations 6 Algebra 5 Differentiable dynamical systems 5 Fourier analysis 5 Global analysis 5 Matrix theory 5 Spectral theory (Mathematics) 5 Global differential geometry 4 Matrices 4 Partial differential equations 4 Banach algebras 3 Computer science 3 Electromagnetic theory 3 Functional equations 3 Group theory 3 Number theory 3