10,328 research outputs found
Quasi-SLCA based Keyword Query Processing over Probabilistic XML Data
The probabilistic threshold query is one of the most common queries in
uncertain databases, where a result satisfying the query must be also with
probability meeting the threshold requirement. In this paper, we investigate
probabilistic threshold keyword queries (PrTKQ) over XML data, which is not
studied before. We first introduce the notion of quasi-SLCA and use it to
represent results for a PrTKQ with the consideration of possible world
semantics. Then we design a probabilistic inverted (PI) index that can be used
to quickly return the qualified answers and filter out the unqualified ones
based on our proposed lower/upper bounds. After that, we propose two efficient
and comparable algorithms: Baseline Algorithm and PI index-based Algorithm. To
accelerate the performance of algorithms, we also utilize probability density
function. An empirical study using real and synthetic data sets has verified
the effectiveness and the efficiency of our approaches
2,2-Dimethyl-5-(2-naphthylÂaminoÂmethylÂene)-1,3-dioxane-4,6-dione
There are two unique molÂecules in the asymmetric unit of the title compound, C17H15NO4, which are linked into chains via interÂmolecular NâHâŻO and CâHâŻO interÂactions; the chains are linked via weak CâHâŻO interÂactions, forming a parallel sheet structure. The molecule is approximately planar, with dihedral angles of 19.91â
(4) and 11.06â
(4)° between the naphthyl ring and the aminoÂmethylÂene group, and between the aminoÂmethylÂene unit and the planar part of the dioxane ring, respectively. The dioxane ring adopts a half-boat conformation, with the C atom between the dioxane O atoms 0.595â
(8)â
Ă
out of the plane through the remaining atoms. The molÂecule has an intraÂmolecular NâHâŻO hydrogen bond which stabilizes the planar conformation
2,2-Dimethyl-5-(1-naphthylÂaminoÂmethylÂene)-1,3-dioxane-4,6-dione
The benzyl ring of the title compound, C17H15NO4, is twisted away from the plane defined by five atoms of the dioxane ring by 34.83â
(4)°. The dioxane ring exhibits a half-boat conformation, with the C atom between the dioxane O atoms 0.571â
(8)â
Ă
out of the plane through the remainder of the ring. An intraÂmolecular NâHâŻO hydrogen bond may contribute to the stabilization of the planar conformation of the molÂecule. In the crystal, inversion dimers linked by pairs of CâHâŻO bonds occur
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