943 research outputs found
Abstract involutions of algebraic groups and of Kac-Moody groups
Based on the second author's thesis in this article we provide a uniform
treatment of abstract involutions of algebraic groups and of Kac-Moody groups
using twin buildings, RGD systems, and twisted involutions of Coxeter groups.
Notably we simultaneously generalize the double coset decompositions
established by Springer and by Helminck-Wang for algebraic groups and by
Kac-Wang for certain Kac-Moody groups, we analyze the filtration studied by
Devillers-Muhlherr in the context of arbitrary involutions, and we answer a
structural question on the combinatorics of involutions of twin buildings
raised by Bennett-Gramlich-Hoffman-Shpectorov
Recommended from our members
A Study of Assimilation Bias in Name-Based Sampling of Migrants
The use of personal names for screening is an increasingly popular sampling technique for migrant populations. Although this is often an effective sampling procedure, very little is known about the properties of this method. Based on a large German survey, this article compares characteristics of respondents whose names have been correctly classified as belonging to a migrant population with respondentswho aremigrants and whose names have not been classified as belonging to a migrant population. Although significant differences were found for some variables even with some large effect sizes, the overall bias introduced by name-based sampling (NBS) is small as long as procedures with small false-negative rates are employed
Recommended from our members
Ein neues Verfahren fĂŒr namensbasierte Zufallsstichproben von Migranten
The set of best methods for sampling mi- grant populations includes name-based sampling. So far this is done using either ad-hoc lists or onomastic dictionaries for the classi cation of names. This paper pro- poses a new name-based procedure, which uses a Bayes-classi er for the n-grams of the name. The new procedure is fault-tol- erant of alternate spellings, and also allows the classi cation of names that are not found in dictionaries. It was tested using the names of about 1.600 foreigners in the PASS panel. Finally, a CATI survey based on the new method in Hesse is described
The relationship of alignment hyperacuity to stereopsis
Human ability to monocularly detect spatial misalignment is functionally more precise than predicted by the diameter of one foveal cone. The spatial thresholds for vernier alignment are approximately 8 to 13 arc seconds of visual angle, which is more sensitive than expected. Although threshold stereopsis (another hyperacuity) seems to be approximately double alignment hyperacuity values, studies have not conclusively shown a definite relationship to ex1st. Additionally, these measurements have not been widely tested in clinical settings. This study examines the correlation between threshold stereoacuity and the monocular alignment hyperacuity measures. Twenty six subjects were evaluated measuring threshold stereopsis with the Mentor BVAT II Visual Acuity Tester and monocular alignment hyperacuity with software designed at Pacific University College of Optometry. This study supports a relationship of sum of one standard deviation of hyperacuity data distributed for each eye with stereopsis. However, the relationship is not statistically significant, most likely due to the lack of testing precision and variability in individual performance, specifically in binocular function and appreciation of stereopsis. Increased knowledge in the areas of monocular alignment hyperacuity and threshold stereopsis may aid optometric practitioners to better understand how these two factors play a role in such clinical conditions as unexplained asthenopia, amblyopia, strabismus and stereoacuity potential. However, clinical testing of an individual patient would not seem appropriate with this testing paradigm
Loops under Strategies ... Continued
While there are many approaches for automatically proving termination of term
rewrite systems, up to now there exist only few techniques to disprove their
termination automatically. Almost all of these techniques try to find loops,
where the existence of a loop implies non-termination of the rewrite system.
However, most programming languages use specific evaluation strategies, whereas
loop detection techniques usually do not take strategies into account. So even
if a rewrite system has a loop, it may still be terminating under certain
strategies.
Therefore, our goal is to develop decision procedures which can determine
whether a given loop is also a loop under the respective evaluation strategy.
In earlier work, such procedures were presented for the strategies of
innermost, outermost, and context-sensitive evaluation. In the current paper,
we build upon this work and develop such decision procedures for important
strategies like leftmost-innermost, leftmost-outermost,
(max-)parallel-innermost, (max-)parallel-outermost, and forbidden patterns
(which generalize innermost, outermost, and context-sensitive strategies). In
this way, we obtain the first approach to disprove termination under these
strategies automatically.Comment: In Proceedings IWS 2010, arXiv:1012.533
Recommended from our members
Impact of Electric Industry Structure on High Wind Penetration Potential
This paper attempts to evaluate which balancing area (BA) characteristics best accommodate wind energy
Behavior of Forging Steels under Cyclic Loading â the Benefit of AirâHardening Martensites
The development of airâhardening martensitic forging (LHD: luft hĂ€rtend duktil) steels offers high material performance with a short and simple process route. In this study, five alloys (L1âL5), based on the existing LHD alloy concept but with different contents of aluminum, titanium, boron, and molybdenum, are cast at laboratory scale. The casted blocks are hot forged into semifinished products and cooled in air (uncontrolled). The tensile properties, the Charpy Vânotch impact energy, the cyclic material behavior, and the fatigue strength of the alloys L1âL5 are opposed to each other. Furthermore, the material properties are compared with the standard quench and tempered (Q+T) steel 42CrMo4 (reference material) and ranked against previously developed forging steels. The tensile properties and Charpy Vânotch impact energy are comparable with those of the reference material, whereas the new alloy concepts show a significantly higher cyclic yield strength and fatigue strength
Electronic properties of alkali-metal loaded zeolites -- a "supercrystal" Mott insulator
First-principles band calculations are performed for the first time for an
open-structured zeolite (LTA) with guest atoms (potassium) introduced in their
cages. A surprisingly simple band structure emerges, which indicates that this
system may be regarded as a "supercrystal", where each cluster of guest atoms
with diameter 10\AA acts as a "superatom" with well-defined - and
-like orbitals, which in turn form the bands around the Fermi energy. The
calculated Coulomb and exchange energies for these states turn out to be in the
strongly-correlated regime. With the dynamical mean-field theory we show the
system should be on the Mott-insulator side, and, on a magnetic phase diagram
for degenerate-orbital systems, around the ferromagnetic regime, in accord with
experimental results. We envisage this class of systems can provide a new
avenue for materials design.Comment: 4 pages, 4 figure
- âŠ