Yifeng Zheng

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Linguistic research and natural language processing employ large repositories of ordered trees. XML, a standard ordered tree model, and XPath, its associated language, are natural choices for linguistic data and queries. However, several important expressive features required for linguistic queries are missing or hard to express in XPath. In this paper, we(More)
Current techniques for storing XML using relational technology consider the structure of an XML document but ignore its semantics as expressed by keys or functional dependencies. However, when the semantics of a document are considered redundancy may be reduced, node identifiers removed where value-based keys are available, and semantic constraints(More)
Streaming XPath evaluation algorithms must record a potentially exponential number of pattern matches when both predicates and descendant axes are present in queries, and the XML data is recursive. In this paper, we use a compact data structure to encode these pattern matches rather than storing them explicitly. We then propose a polynomial time streaming(More)
As XML becomes a standard for data representation on the internet, there is a growing interest in storing XML using relational database technology. To date, none of these techniques have considered the semantics of XML as expressed by keys and foreign keys. In this paper, we present a storage mapping which preserves not only the content and structure of XML(More)
With phylogenetics becoming increasingly important in biomedical research, the number of phylogenetic studies is increasing rapidly and huge mount of phy-logenetic data has been generated and stored in databases. How to efficiently extract information from the data has become an important research problem. In this paper, we focus on a class of important(More)
Evolutionary and systems biology increasingly rely on the construction of large phylogenetic trees which represent the relationships between species of interest. As the number and size of such trees increases, so does the need for efficient data storage and query capabilities. Although much attention has been focused on XML as a tree data model,(More)