A countable group Γ is called shift-minimal if every non-trivial measure preserving action of Γ weakly contained in the Bernoulli shift Γ y ([0, 1] , λ ) is free. We show that any group Γ whose reduced C∗-algebra Cr(Γ) admits a unique tracial state is shift-minimal, and that any group Γ admitting a free measure preserving action of cost> 1 contains a finite normal subgroup N such that Γ/N is sh...

It is a well-know fact that externally positive linear systems may fail to have a minimal positive realization. In order to investigate these cases, we introduce the notion of minimal eventually positive realization, for which the state update matrix becomes positive after a certain power. Eventually positive realizations capture the idea that in the impulse response of an externally positive s...

The problems of minimal state-space realization for a three-dimensional (3-D) separable-denominator digital filter and analysis of l2-sensitivity for the realized 3-D state-space model are investigated. First, a 3-D transfer function with separable denominator is expressed as a cascade connection of three one-dimensional (1D) transfer functions by applying a minimal decomposition technique. Nex...

the paper discusses the current state of research concerning railway network timetabling and traffic management. timetable effectiveness is governed by frequency, regularity, accurate running, recovery and layover times, as well as minimal headway, buffer times and waiting times. analytic (queuing) models and stochastic microsimulation are predominantly used for estimation of waiting times and ...

An upper bound on the minimal state complexity of codes from the Hermitian function field and some of its subfields is derived. Coordinate orderings under which the state complexity of the codes is not above the bound are specified. For the self-dual Hermitian code it is proved that the bound coincides with the minimal state complexity of the code. Finally, it is shown that Hermitian codes over...