L. Klotz

activity

20012026

most citedA duality method in prediction theory of multivariate stationary sequences

11 citations · 15 across the 9 of their papers we have counts for

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7 papers · 1 filter

math.FA2026

Extremal representations of functions of matrices and applications to multivariate prediction

Michael Frank, Lutz Klotz, Andreas Lasarow

Motivated by two seminal results of multivariate prediction theory by Helson and Lowdenslager and by Wiener and Masani we prove extremal representations of functions of matrices an…

math.FA2026

Remarks on infimum and maximal lower bounds of a set of bounded self-adjoint operators

Matthias Günther, Lutz Klotz

The notions of infimum and maximal lower bounds of a set $M$ of bounded self-adjoint operators were mainly studied for a set $M$ of two elements. The present pa…

math.FA2017

Duality results for a general trigonometric approximation problem

Lutz Klotz, Conrad Mädler

Let $α \in (1, \infty)$ and $μ$ be a regular finite Borel measure on a locally compact abelian group. The paper deals with a general trigonometric approximation problem in $L^{α} (μ)$ , w…

math.FA2017

H-Regular Borel measures on locally compact abelian groups

Lutz Peter Klotz, Juan Miguel Medina

Let $G$ be an LCA group, $H$ a closed subgroup, $Γ$ the dual group of $G$ . In accordance with analogous notions in prediction theory the classes of $H$ -regular and $H$ -sing…

math.FA2017

Density of spaces of trigonometric polynomials with frequencies from a subgroup in $L^{α}$ -spaces

Juan Miguel Medina, Lutz Peter Klotz, Manfred Riedel

Let $G$ be an LCA group, $H$ a closed subgroup, $Γ$ the dual group of $G$ and $μ$ be a regular finite non-negative Borel measure on $Γ$ . We give some necessary and…

math.FA2017★ 4 cited

A generalized Schur complement for non-negative operators on linear space

J. Friedrich, M. Günther, L. Klotz

Extending the corresponding notion for matrices or bounded linear operators on a Hilbert space we define a generalized Schur complement for a non-negative linear operator mapping a…

math.FA2016

A necessary condition for certain functions to preserve positive semi-definiteness on partitioned matrices

Lutz Klotz, Conrad Mädler

If $f$ is a symmetric complex-valued function on the $m$ -fold Cartesian product of the set of non-negative reals and $A$ is a positive semi-definite $m \times m$ matrix with eigenva…

Extremal representations of functions of matrices and applications to multivariate prediction

Remarks on infimum and maximal lower bounds of a set of bounded self-adjoint operators

Duality results for a general trigonometric approximation problem

H-Regular Borel measures on locally compact abelian groups

Density of spaces of trigonometric polynomials with frequencies from a subgroup in Lα-spaces

A generalized Schur complement for non-negative operators on linear space

A necessary condition for certain functions to preserve positive semi-definiteness on partitioned matrices

Density of spaces of trigonometric polynomials with frequencies from a subgroup in $L^{α}$ -spaces