22,732 research outputs found
Restructuring and simplifying rule bases.
Rule bases are commonly acquired, by expert and/or knowledge engineer, in a form which is well suited for acquisition purposes. When the knowledge base is executed, however, a different structure may be required. Moreover, since human experts normally do not provide the knowledge in compact chunks, rule bases often suffer from redundancy. This may considerably harm efficiency. In this paper a procedure is examined to transform rules that are specified in the knowledge acquisition process into an efficient rule base by way of decision tables. This transformation algorithms allows the generation of a minimal rule representation of the knowledge, and verification and optimization of rule bases and other specification (e.g. legal texts, procedural descriptions, ...). The proposed procedures are fully supported by the PROLOGA tool.
Whitney coverings and the tent spaces for the Gaussian measure
We introduce a technique for handling Whitney decompositions in Gaussian
harmonic analysis and apply it to the study of Gaussian analogues of the
classical tent spaces of Coifman, Meyer and Stein.Comment: 13 pages, 1 figure. Revised version incorporating referee's comments.
To appear in Arkiv for Matemati
Tunable quantum spin Hall effect in double quantum wells
The field of topological insulators (TIs) is rapidly growing. Concerning
possible applications, the search for materials with an easily controllable TI
phase is a key issue. The quantum spin Hall effect, characterized by a single
pair of helical edge modes protected by time-reversal symmetry, has been
demonstrated in HgTe-based quantum wells (QWs) with an inverted bandgap. We
analyze the topological properties of a generically coupled HgTe-based double
QW (DQW) and show how in such a system a TI phase can be driven by an
inter-layer bias voltage, even when the individual layers are non-inverted. We
argue, that this system allows for similar (layer-)pseudospin based physics as
in bilayer graphene but with the crucial absence of a valley degeneracy.Comment: 9 pages, 8 figures, extended version (accepted Phys. Rev. B
Fluctuation-induced Topological Quantum Phase Transitions in Quantum Spin Hall and Quantum Anomalous Hall Insulators
We investigate the role of quantum fluctuations in topological quantum phase
transitions of quantum spin Hall insulators and quantum anomalous Hall
insulators. Employing the variational cluster approximation to obtain the
single-particle Green's function of the interacting many-body system, we
characterize different phases by direct calculation of the recently proposed
topological order parameter for interacting systems. We pinpoint the influence
of quantum fluctuations on the quantum spin Hall to Mott insulator transition
in several models. Furthermore, we propose a general mechanism by which a
topological quantum phase transition can be driven by the divergence of the
self energy induced by interactions
The 85$Rb(p,n)85Sr reaction and the modified proton optical potential
The cross sections of the astrophysically relevant 85$Rb(p,n)85Srg,m reaction
have been measured between Ec.m. = 2.16 and 3.96 MeV. The cross sections have
been derived by measuring the gamma radiation following the beta decay of the
reaction products. A comparison with the predictions of Hauser-Feshbach
calculations using the NON-SMOKER code confirms a recently derived modification
of the global optical proton potential.Comment: CGS XIII conferenc
Further Evidence for a Merger Origin for the Thick Disk: Galactic Stars Along Lines-of-sight to Dwarf Spheroidal Galaxies
The history of the Milky Way Galaxy is written in the properties of its
stellar populations. Here we analyse stars observed as part of surveys of local
dwarf spheroidal galaxies, but which from their kinematics are highly probable
to be non-members. The selection function -- designed to target metal-poor
giants in the dwarf galaxies, at distances of ~100kpc -- includes F-M dwarfs in
the Milky Way, at distances of up to several kpc. Thestars whose motions are
analysed here lie in the cardinal directions of Galactic longitude l ~ 270 and
l ~ 90, where the radial velocity is sensitive to the orbital rotational
velocity. We demonstrate that the faint F/G stars contain a significant
population with V_phi ~ 100km/s, similar to that found by a targeted, but
limited in areal coverage, survey of thick-disk/halo stars by Gilmore, Wyse &
Norris (2002). This value of mean orbital rotation does not match either the
canonical thick disk or the stellar halo. We argue that this population,
detected at both l ~ 270 and l ~ 90, has the expected properties of `satellite
debris' in the thick-disk/halo interface, which we interpret as remnants of the
merger that heated a pre-existing thin disk to form the thick disk.Comment: Accepted, Astrophysical Journal Letter
The Gardener and the Sick Garden: How Not to Address the Planet\u27s Environmental Issues
A truly workable environmental strategy would start by being grounded in better, more realistic and empirically accurate models of how nature works, how humans behave, and humankind\u27s relationship to nature. Such an environmental policy would realize that the gardener and the garden are not separate, but one. And this environmental policy would embrace two correlative legal norms: (1) we should recognize a positive right, held by both humans and their natural surroundings, to environmental conditions that may sustain human survivability\u27; and (2) we should impose an affirmative duty on humans to promote and support natural systems
The Generation of Fullerenes
We describe an efficient new algorithm for the generation of fullerenes. Our
implementation of this algorithm is more than 3.5 times faster than the
previously fastest generator for fullerenes -- fullgen -- and the first program
since fullgen to be useful for more than 100 vertices. We also note a
programming error in fullgen that caused problems for 136 or more vertices. We
tabulate the numbers of fullerenes and IPR fullerenes up to 400 vertices. We
also check up to 316 vertices a conjecture of Barnette that cubic planar graphs
with maximum face size 6 are hamiltonian and verify that the smallest
counterexample to the spiral conjecture has 380 vertices.Comment: 21 pages; added a not
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