8920901
Exploit Sequencing to Accelerate XML Twig Query Answering
Speeding up query evaluation in large XML repositories becomes a challenging and all-important problem with vast XML-related applications arising. In this paper, we present SCALER, an efficient algorithm for XML query answering based on UDFTS and effective twig structure matching scheme. UDFTS not only constructs a one-to-one correspondence between trees and sequences but also maintains critical parent-child relationships for twig structure matching. With SCALER, XML queries can be performed by subsequence matching without breaking twigs into sub paths and evaluating these paths individually. Thus, costly join operations can be avoided elegantly. We also show the correctness of query answering by eliminating false dismissals and false alarms naturally in SCALER. By a thorough experimental study on various real-life data, we prove the efficiency and scalability of SCALER over the previous known alternative.
32509112
A Highly Adaptable Web Information Extractor Using Graph Data Model
We present an approach to build highly adaptable extractor for collecting data from diverse Web sites. This approach uses Graph Model to represent content and structures as well as their various types of features. The generated graph is accompanied by a script in a special language called GQML containing the extraction rules. The running of the script transforms the graph into a specified format such as XML file that stores data from various Web sites in a uniform format. The experimental results show the presented approach is both effective and efficient.
46516744
Efficient Keyword Search over Data-Centric XML Documents
We in this paper investigate keyword search over data-centric XML documents. We first present a novel method to divide an XML document into self-integrated subtrees, which are connected subtrees and can capture different structural information of the XML document. We then propose the meaningful self-integrated trees, which contain all the keywords and describe how the keywords are interrelated, to answer keyword search over XML documents. In addition, we introduce the B+-tree index to accelerate the retrieval of those meaningful self-integrated trees. Moreover, to further enhance the performance of keyword search, we present Bloom Filter to improve the efficiency of generating those meaningful self-integrated trees. Finally, we conducted extensive experiments to evaluate the performance of our method, and the experimental results demonstrate that our method achieves high efficiency and outperforms the existing approaches significantly.
28810751
Counting Graph Matches with Adaptive Statistics Collection
High performance of query processing in large scale graph-structured data poses a pressing demand for high-quality statistics collection and selectivity estimation. Precise and succinct statistics collection about graph-structured data plays a crucial role for graph query selectivity estimation. In this paper, we propose the approach SMT, Succinct Markov Table, which achieves high precision in selectivity estimation with low memory space consumed. Four core notions of SMT are constructing, refining, compressing and estimating. The efficient algorithm SMTBuilder provides facility to build adaptive statistics model in the form of SMT. Versatile optimization rules, which investigate local bi-directional reachability, are introduced in SMT refining. During compressing, affective SMT grouping techniques are introduced. Statistical methods are used for selectivity estimations of various graph queries basing on SMT, especially for twig queries. By a thorough experimental study, we demonstrate SMT's advantages in accuracy and space by comparing with previously known alternative, as well as the preferred optimization rules and compressing technique that would favor different real-life data.
16295185
2D/3D Web Visualization on Mobile Devices
Visualization is able to present the rich Web information intuitively and make the Web search/mining more productive. Mobile computing is able to provide the flexibility of working anytime and anywhere. Therefore, it is natural to combine the two techniques for intriguing applications. However, the technical limitations of mobile devices make it difficult to port well-designed visualization methods from desktop computers to mobile devices. In this paper, we present what we learned on engineering 3D Web visualization on both high-end and low-end mobile devices as the MWeb3D framework, which forms a distributed pipeline that move intensive computation from the mobile devices to server systems. Some important issues of this strategy include: (1) separating visualization from graphics rendering, (2) encoding visual presentation for transmitting via bandwidth-limited wireless connections, (3) user interaction on mobile devices, and (4) highly efficient graphics rendering on the mobile devices. We will show fruitful experiments on both PDA and mobile phone with photos taken from both simulator and real mobile devices.
28964163
Hidden Conditioned Homomorphism for XPath Fragment Containment
As a query language for navigating XML trees and selecting a set of element nodes, XPath is ubiquitous in XML applications. One important issue of XPath queries is checking containment. In particular, we investigate a frequently used fragment of XPath that consists of node tests, the child axis (/), the descendant axis (//), branches ([]) and label wildcards (*). For special classes of pattern trees, the homomorphism algorithm returns false negatives. In order to address this problem, we propose two containment techniques, conditioned homomorphism and hidden conditioned homomorphism, and then present sound algorithms to check containment. The analytical result is given with an experiment.
33716862
Computation of Sparse Data Cubes with Constraints
For a data cube there are always constraints between dimensions or between attributes in a dimension, such as functional dependencies. We introduce the problem that when there are functional dependencies, how to use them to speed up the computation of sparse data cubes. A new algorithm CFD is presented to satisfy this demand. CFD determines the order of dimensions by considering their cardinalities and functional dependencies between them together. It makes dimensions with functional dependencies adjacent and their codes satisfy monotonic mapping, thus reduces the number of partitions for such dimensions. It also combines partitioning from bottom to up and aggregate computation from top to bottom to speed up the computation further. In addition CFD can efficiently compute a data cube with hierarchies from the smallest granularity to the coarsest one, and at most one attribute in a dimension takes part in the computation each time. The experiments have shown that the performance of CFD has a significant improvement.
8854003
Characterization of edge-colored complete graphs with properly colored Hamilton paths
An edge-colored graph H is properly colored if no two adjacent edges of H have the same color. In 1997, J. Bang-Jensen and G. Gutin conjectured that an edgecolored complete graph G has a properly colored Hamilton path if and only if G has a spanning subgraph consisting of a properly colored path C0 and a (possibly empty) collection of properly colored cycles C1, C2, . . . , Cd such that V (Ci) ∩ V (Cj) = ∅ provided 0 ≤ i < j ≤ d. We prove this conjecture.