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-naphthyl­amino­methyl­ene)-1,3-dioxane-4,6-dione

There are two unique mol­ecules in the asymmetric unit of the title compound, C17H15NO4, which are linked into chains via inter­molecular N—H⋯O and C—H⋯O inter­actions; the chains are linked via weak C—H⋯O inter­actions, forming a parallel sheet structure. The molecule is approximately planar, with dihedral angles of 19.91 (4) and 11.06 (4)° between the naphthyl ring and the amino­methyl­ene group, and between the amino­methyl­ene 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 0.595 (8) Å out of the plane through the remaining atoms. The mol­ecule has an intra­molecular N—H⋯O hydrogen bond which stabilizes the planar conformation

2,2-Dimethyl-5-(1-naphthyl­amino­methyl­ene)-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 34.83 (4)°. The dioxane ring exhibits a half-boat conformation, with the C atom between the dioxane O atoms 0.571 (8) Å out of the plane through the remainder of the ring. An intra­molecular N—H⋯O hydrogen bond may contribute to the stabilization of the planar conformation of the mol­ecule. In the crystal, inversion dimers linked by pairs of C—H⋯O bonds occur