Free algebras and noncommutative power series in the analysis of nonlinear control systems: an application to approximation problems
The paper contains a consistent presentation of the approach developed by the authors to analysis of nonlinear control systems, which exploits ideas and techniques of formal power series of independent noncommuting variables and the corresponding free algebras. The main part of the paper was conceived with a view of comparing our results with the results obtained by use of the differential-geometric approach. We consider control-linear systems with m controls. In a free associative algebra with...