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On sparsity of approximate solutions to max-plus linear systems

Pingke Li (2024)

Kybernetika

When a system of one-sided max-plus linear equations is inconsistent, the approximate solutions within an admissible error bound may be desired instead, particularly with some sparsity property. It is demonstrated in this paper that obtaining the sparsest approximate solution within a given L error bound may be transformed in polynomial time into the set covering problem, which is known to be NP-hard. Besides, the problem of obtaining the sparsest approximate solution within a given L 1 error bound...

On spectral properties of linear combinations of idempotents

Hong-Ke Du, Chun-Yan Deng, Mostafa Mbekhta, Vladimír Müller (2007)

Studia Mathematica

Let P,Q be two linear idempotents on a Banach space. We show that the closedness of the range and complementarity of the kernel (range) of linear combinations of P and Q are independent of the choice of coefficients. This generalizes known results and shows that many spectral properties of linear combinations do not depend on their coefficients.

On systems of linear algebraic equations in the Colombeau algebra

Jan Ligęza, Milan Tvrdý (1999)

Mathematica Bohemica

From the fact that the unique solution of a homogeneous linear algebraic system is the trivial one we can obtain the existence of a solution of the nonhomogeneous system. Coefficients of the systems considered are elements of the Colombeau algebra ¯ of generalized real numbers. It is worth mentioning that the algebra ¯ is not a field.

On the angles between certain arithmetically defined subspaces of 𝐂 n

Robert Brooks (1987)

Annales de l'institut Fourier

If { v i } and { w j } are two families of unitary bases for C n , and θ is a fixed number, let V n and W n be subspaces of C n spanned by [ θ · n ] vectors in { v i } and { w j } respectively. We study the angle between V n and W n as n goes to infinity. We show that when { v i } and { w j } arise in certain arithmetically defined families, the angles between V n and W n may either tend to 0 or be bounded away from zero, depending on the behavior of an associated eigenvalue problem.

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