@phdthesis{Jordan2008,
  author    = {Jordan, Jens},
  title     = {Reachable sets of numerical iteration schemes : a system semigroup approach},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28416},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {We investigate iterative numerical algorithms with shifts as nonlinear discrete-time control systems. Our approach is based on the interpretation of reachable sets as orbits of the system semigroup. In the first part we develop tools for the systematic analysis of the structure of reachable sets of general invertible discrete-time control systems. Therefore we merge classical concepts, such as geometric control theory, semigroup actions and semialgebraic geometry. Moreover, we introduce new concepts such as right divisible systems and the repelling phenomenon. In the second part we apply the semigroup approach to the investigation of concrete numerical iteration schemes. We extend the known results about the reachable sets of classical inverse iteration. Moreover, we investigate the structure of reachable sets and systemgroup orbits of inverse iteration on flag manifolds and Hessenberg varieties, rational iteration schemes, Richardson's method and linear control schemes. In particular we obtain necessary and sufficient conditions for controllability and the appearance of repelling phenomena. Furthermore, a new algorithm for solving linear equations (LQRES) is derived.},
  subject      = {Nichtlineare Kontrolltheorie},
  language  = {en}
}