Über Typen des orbitalen Stabilitätsverhaltens.
Eine Bemerkung zu einem Satz von W. Hahn aus der Stabilitätstheorie linearer Systeme.
Über Matrizen mit semidefinitem Realteil.
Existenzsätze in der Theorie der Matrizen und lineare Kontrolltheorie.
Spektralradius und Spektralnorm
Bilinear characterizations of companion matrices
Companion matrices of the second type are characterized by properties that involve bilinear maps.
Pairs of k -step reachability and m -step observability matrices
Let V and W be matrices of size n × pk and qm × n, respectively. A necessary and sufficient condition is given for the existence of a triple (A,B,C) such that V a k-step reachability matrix of (A,B) andW an m-step observability matrix of (A,C).
Spectraloid operator polynomials, the approximate numerical range and an Eneström-Kakeya theorem in Hilbert space
We study a class of operator polynomials in Hilbert space which are spectraloid in the sense that spectral radius and numerical radius coincide. The focus is on the spectrum in the boundary of the numerical range. As an application, the Eneström-Kakeya-Hurwitz theorem on zeros of real polynomials is generalized to Hilbert space.
Regular submodules of torsion modules over a discrete valuation domain
A submodule of a -primary module of bounded order is known to be regular if and have simultaneous bases. In this paper we derive necessary and sufficient conditions for regularity of a submodule.
Remarks on inertia theorems for matrices
Reachability matrices and cyclic matrices.
Estimates for projections in Banach spaces and existence of direct complements
Let W and L be complementary subspaces of a Banach space X and let P(W,L) denote the projection on W along L. We obtain a sufficient condition for a subspace M of X to be complementary to W and we derive estimates for the norm of P(W,L) - P(W,M).
Explicit polar decomposition of companion matrices.
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