93B03 Attainable sets
93B05 Controllability
93B07 Observability
93B10 Canonical structure
93B11 System structure simplification
93B12 Variable structure systems
93B15 Realizations from input-output data
93B17 Transformations
93B18 Linearizations
93B20 Minimal systems representations
93B25 Algebraic methods
93B27 Geometric methods (including algebro-geometric)
93B28 Operator-theoretic methods [See also 47A48, 47A57, 47B35, 47N70]
93B29 Differential-geometric methods
93B30 System identification
93B35 Sensitivity (robustness)
93B36 ${H}^\infty$-control
93B40 Computational methods
93B50 Synthesis problems
93B51 Design techniques (robust design, computer-aided design, etc.)
93B52 Feedback control
93B55 Pole and zero placement problems
93B60 Eigenvalue problems
93B99 None of the above, but in this section