UP - logo
FMF, Mathematical Library, Lj. (MAKLJ)
  • Reducibility and triangularizability of semitransitive spaces of operators
    Bernik, Janez, 1967- ...
    A linear space ▫$\mathcal{L}$▫ of operators on a vector space ▫$X$▫ is called semitransitive if,given two nonzero vectors ▫$x,y \in X$▫, there exists an element ▫$A \in \mathcal{L}$▫ such that either ... ▫$y=Ax$▫ or ▫$x=Ay$▫. In this paper we consider semitransitive spaces of operators on a finite dimensional vector space ▫$X$▫ over an algebraically closed field. In particular, we are interested in the existence of nontrivial invariant subspaces of ▫$X$▫ for a semitransitive space ▫$\mathcal{L}$▫. We are able to relate the existence of an invariant subspace for ▫$\mathcal{L}$▫ to the properties of some rank varieties that we associate to ▫$\mathcal{L}$▫. Using this relation we show that, if the dimension of ▫$\mathcal{L}$▫ is the same as the dimension of ▫$X$▫, which is minimal possible, then ▫$\mathcal{L}$▫ is triangularizable. By contrast we show that, from ▫$n=3$▫ onwards, there exists a minimal semitransitive space ▫$L$▫ of dimension ▫$n+1$▫ of operators on an ▫$n$▫-dimensional vector space ▫$X$▫ which is also irreducible. We also give a new characterization of semitransitive spaces of operators on finite dimensional vector spaces.
    Source: Houston journal of mathematics. - ISSN 0362-1588 (Vol. 34, no. 1, 2008, str. 235-247)
    Type of material - article, component part
    Publish date - 2008
    Language - english
    COBISS.SI-ID - 14647641

source: Houston journal of mathematics. - ISSN 0362-1588 (Vol. 34, no. 1, 2008, str. 235-247)

loading ...
loading ...
loading ...