The single-valued extension property for sums and products of commuting operators

It is shown that the sum and the product of two commuting Banach space operators with Dunford's property (C) have the single-valued extension property.     

Sauerstoffbestimmung im Kammerwasser des Auges

Ohne Zusammenfassung     

Die Eindeutigkeit der Ortsobservablen in einer irreduziblen unitären Darstellung bis auf einen Faktor der Galilei-Gruppe

Uniqueness of the Position Observable in an Irreducible Unitary Representation up to a Factor of the Galilei Group. An elementarary quantum mechanical system with non vanishing mass is characterized by a continuous irreducible unitary representation up to a factor of the Galilei group in Hilbert space. An argument is given concerning the continuous iurreducible unitary representations of the universal covering group of the Euclidean group such that the position observable is uniquely determined by the transformation properties under the representation of the Galilei group.     

Recent advances in temporal analysis of GERT networks

An overview of new results on the temporal analysis of GERT networks is given. The methods for evaluating GERT networks presented in this paper are based upon the fact that stochastic processes can be assigned to GERT networks. For special GERT networks, very effective evaluation methods can be found by exploiting some results from the theory of the corresponding stochastic processes. In comparison with the method of simulation, this approach has two advantages: it provides more insight into the structure of the GERT networks in question, and it yields evaluation methods which require less computational effort.

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Zusammenfassung Ein Überblick über neue Resultate zur Zeitplanung von GERT-Netzplänen wird gegeben. Die beschriebenen Methoden zur Auswertung von GERT-Netzplänen basieren darauf, daß GERT-Netzplänen stochastische Prozesse zugeordnet werden können. Für gewisse spe. ielle GERTNetzpläne ergeben sich sehr leistungsfähige Auswertungsmethoden, indem man Resultate aus der Theorie der entsprechenden stochastischen Prozesse ausnutzt. Im Vergleich zur Simulation weist diese Vorgehensweise zwei Vorzüge auf: Sie erlaubt mehr Einblick in die Struktur der betrachteten GERT-Netzpläne, und sie liefert Auswertungsmethoden, die weniger Rechenaufwand als die Simulation erfordern.

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An invited survey.     

Infrared reflectivity of Ag6Ge10P12

Infrared reflectivity spectra of p-type Ag₆Ge₁₀P₁₂ single crystals were measured at room temperature in the wavenumber range from 180 to 4000 cm^-1. Fits to a dielectric function including contributions from lattice oscillators and free carriers gave the parameters of five lattice vibrational modes and an effective hole mass of m_p/m_o = 2.3.     

Algorithms for single-machine scheduling with stochastic outtree precedence relations to minimize expected weighted flow time or maximum expected lateness

Stochastic single-machine scheduling problems with special tree-like GERT precedence constraints and expected weighted flow time or maximum expected lateness as objective functions are considered. To obtain polynomial algorithms for these problems, Smith's ratio rule and Lawler's rule for the deterministic problems 1¦outtree¦w _v C _v and 1¦prec¦f _max , respectively, are generalized.