Ara es mostren els items 21-31 de 31

    • Simultaneous versal deformations of endomorphisms and invariant subspaces 

      Compta Creus, Albert; Helmke, Uwe; Peña Carrera, Marta; Puerta Coll, Xavier (2004)
      Article
      Accés obert
      We study the set M of pairs (f; V ), defined by an endomorphism f of Fn and a d- dimensional f–invariant subspace V . It is shown that this set is a smooth manifold that defines a vector bundle on the Grassmann manifold. ...
    • Stability of (A,B)-invariant subspaces 

      Peña Carrera, Marta; Puerta Coll, Xavier; Puerta Sales, Ferran (2005)
      Article
      Accés obert
      Given a pair of matrices (A;B) we study the stability of their invariant subspaces from the geometry of the manifold of quadruples (A;B; S; F) where S is an (A;B)-invariant subspace and F is such that (A + BF)S ½ S. In ...
    • Stability of <math>(A, B)</math>-invariant subspaces 

      Puerta Sales, Ferran; Puerta Coll, Xavier (2003)
      Report de recerca
      Accés obert
      Given a pair of matrices (A,B) we study the stability of their invariant subspaces from a geometric point of view. The main tool is the manifold of quadruples((A;B); F; S) where S is an (A,B)-invariant subspace and F is ...
    • Stratification and bundle structure of the set of conditioned invariant subspaces in the general case 

      Ferrer Llop, Josep; Puerta Sales, Ferran; Puerta Coll, Xavier (2000)
      Article
      Accés obert
      We extend some known results about the smooth stratification of the set of conditioned invariant subspaces for a general pair $(C,A)\in\w C^n\times\w C^{n+m}$ without any assumption on the observability. More precisely ...
    • Stratification and bundle structure of the set of conditioned invariant subspaces in the general case 

      Ferrer Llop, Josep; Puerta Sales, Ferran; Puerta Coll, Xavier (2003)
      Article
      Accés obert
      We extend some known results about the smooth stratification of the set of conditioned invariant subspaces for a general pair $(C,A)\in\w C^n\times\w C^{n+m}$ without any assumption on the observability. More precisely ...
    • Stratification and bundle structure of the set of general (A,B)-invariant subspaces 

      Ferrer Llop, Josep; Puerta Sales, Ferran; Puerta Coll, Xavier (1998)
      Article
      Accés obert
      Given (A,B) in Hom(C^(n+m) C^n), we prove that the set of (A,B)-invariant subspaces having a fixed Brunovsky-Kronecker structure is a submanifold of the corresponding grassman manifold, and we compute its dimension. Also, ...
    • The geometry of the set of conditioned invariant flags 

      Puerta Coll, Xavier (1999)
      Working paper
      Accés obert
    • The topology of the set of conditioned invariant subspaces 

      Puerta Coll, Xavier; Helmke, Uwe (1999)
      Article
      Accés obert
      We consider the topology of the set of conditioned invariant subspaces of an observable pair $(C,A)$ of a fixed dimension. By fixing the observability indices of the restricted system, a stratification by finitely many ...
    • Versal deformations in generalized flag manifolds 

      Puerta Coll, Xavier (2004)
      Article
      Accés obert
      We find explicit miniversal deformations of flags in the generalized flag manifolds, with regard a natural equivalence relation defined by the group action that keeps fixed the reference flag.
    • Versal deformations in orbit spaces 

      Puerta Sales, Ferran; Puerta Coll, Xavier; Tarragona Romero, Sonia (2003)
      Article
      Accés obert
      Given an orbit space $M/\Gamma$ and an equivalence relation defined in it by means of the action of a group $G$, we obtain a miniversal deformation of an orbit through a miniversal deformation in $M$ with regard to a ...
    • Versal deformations in orbit spaces of matrices 

      Puerta Sales, Ferran; Puerta Coll, Xavier; Tarragona Romero, Sonia (2002)
      Article
      Accés obert
      Given an orbit space of matrices $M/\Gamma$ and an equivalence relation defined in it by means of the action of a group $G$, we obtain a miniversal deformation of an orbit through a minivesal deformation in $M$ with regard ...