Incremental controlled relaxation of failing flexible queries

In this paper, we discuss an approach for relaxing a failing query in the context of flexible (or fuzzy) querying. The approach relies on the notion of a parameterized proximity relation which is defined in a relative way. We show how such a proximity relation allows for transforming a gradual predicate into an enlarged one. The resulting predicate is semantically close to the original one and it is obtained by a simple fuzzy arithmetic operation. Such a transformation provides the basis for a flexible query relaxation which can be controlled in a non-empirical rigorous way without requiring any additional information from the user. We also show how the search for a non-failing relaxed query over the lattice of relaxed queries can be improved by exploiting the notion of Minimal Failing Sub-queries derived from the failing query.     

A cooperative treatment of the plethoric answers problem in RDF

Knowledge and Information Systems - When querying Knowledge Bases, users are faced with large sets of data, often without knowing their underlying structures. It follows that users may make...     

Theoretical investigation of electronic performance,half-metallicity,and magnetic properties of Cr-substituted BaTe

We have investigated the structural, electronic, and ferromagnetic properties of chromium (Cr)-doped rocksalt BaTe (\(\hbox {Ba}_{1-x}\hbox {Cr}_{x}\hbox {Te}\)) compounds with compositions \(x = 0.25\), 0.5, and 0.75, based on density functional theory with generalized gradient approximation of Wu–Cohen (GGA-WC) and Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential using the WIEN2k package. We found that the electronic structure showed half-metallic ferromagnetic character with spin polarization of 100 % around the Fermi level. In addition, the minority-spin bands depicted a half-metallic ferromagnetic (HMF) gap and half-metallic (HM) gap. The improved HMF and HM gaps found with the TB-mBJ potential are higher than with the GGA-WC approximation. These large HM gaps make \(\hbox {Ba}_{1-x} \hbox {Cr}_{x}\hbox {Te}\) compounds promising candidates for use in spintronics applications.     

Database preference queries��a possibilistic logic approach with symbolic priorities

The paper presents a new approach to database preference queries, where preferences are represented in a possibilistic logic manner, using symbolic weights. The symbolic weights may be processed without assessing their precise value, which leaves the freedom for the user to not specify any priority among the preferences. The user may also enforce a (partial) ordering between them, if necessary. The approach can be related to the processing of fuzzy queries whose components are conditionally weighted in terms of importance. In this paper, importance levels are symbolically processed, and refinements of both Pareto ordering and minimum ordering are used. The representational power of the proposed setting is stressed, while the approach is compared with database Best operator-like methods and with the CP-net approach developed in artificial intelligence. The paper also provides a structured and rather broad overview of the different lines of research in the literature dealing with the handling of preferences in database queries.     

Electronic and Ferromagnetic Properties of 3<Emphasis Type="Italic">d</Emphasis>(V)-Doped (BaS) Barium Sulfide

The objective of this study is to investigate the electronic structure and ferromagnetic properties of barium sulfide (BaS) doped with vanadium (V) impurity. The calculations were performed by using the first-principle calculations of density functional theory. The lattice constant of Ba_1?x V _x S decreases with increasing concentration (x) of the V atom. We have found that the Ba_0.75 V _0.25S and Ba_0.5 V _0.5S compounds are half-metallic ferromagnets with total magnetic moments of 3 μ _B per V atom, while for high concentration x = 0.75, the Ba_0.25 V _0.75S becomes nearly half metallic due to broadening of 3d (V) states in the gap. The exchange coupling between the 3d (V) levels and conduction bands is ferromagnetic, confirming the magnetic nature of Ba_1?x V _x S compounds.