On bounded matrices and kinematic similarity

A brief introduction to quaternion matrices and linear algebra and on bounded groups of quaternion matrices

The division algebra of real quaternions, as the only noncommutative normed division real algebra up to isomorphism of normed algebras, is of great importance. In this note, first we present a brief introduction to quaternion matrices and quaternion linear algebra. This, among other things, will help us present the counterpart of a theorem of Herman Auerbach in the setting of quaternions. More ...

1 Kinematic Self-similarity

Self-similarity in general relativity is briefly reviewed and the differences between self-similarity of the first kind (which can be obtained from dimensional considerations and is invariantly characterized by the existence of a homothetic vector in perfect fluid spacetimes) and generalized self-similarity are discussed. The covariant notion of a kinematic self-similarity in the context of rel...

A note on power bounded matrices

Ela a Note on Power Bounded Matrices

We say A is convergent to the matrix X = [xij ] if the sequences (A )ij converge to xij as k → ∞. A matrix is convergent if it is convergent to some matrix. This is a special case of convergence as defined in [4, Definition 10.1], for the matrix sequence {A,A, A, . . . }. In particular, we say A is zero convergent when A is convergent to the zero matrix. We distinguish between convergence and z...

Bounded Semigroups of Matrices

In this note are proved two conjectures of Daubechies and Lagarias. The first asserts that if Z is a bounded set of matrices such that all left infinite products converge, then 8 generates a bounded semigroup. The second asserts the equality of two differently defined joint spectral radii for a bounded set of matrices. One definition involves the conventional spectral radius, and one involves t...