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Abstract-We study the following problem: how to efficiently find in a collection of strings those similar to a given query string? Various similarity functions can be used, such as edit distance, Jaccard similarity, and cosine similarity. This problem is of great interests to a variety of applications that need a high real-time performance, such as data cleaning, query relaxation, and spellchecking. Several algorithms have been proposed based on the idea of merging inverted lists of grams generated from the strings. In this paper we make two contributions. First, we develop several algorithms that can greatly improve the performance of existing algorithms. Second, we study how to integrate existing filtering techniques with these algorithms, and show that they should be used together judiciously, since the way to do the integration can greatly affect the performance. We have conducted experiments on several real data sets to evaluate the proposed techniques.

In this paper, we propose an IR-style approach which basically utilizes the statistics of underlying XML data to address these challenges. We first propose specific guidelines that a search engine should meet in both search intention identification and relevance oriented ranking for search results. Then based on these guidelines, we design novel formulae to identify the search for nodes and search via nodes of a query, and present a novel XML TF*IDF ranking strategy to rank the individual matches of all possible search intentions. Lastly, the proposed techniques are implemented in an XML keyword search engine called XReal, and extensive experiments show the effectiveness of our approach.

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Searching for all occurrences of a twig pattern in an XML document is an important operation in XML query processing. Recently a holistic method T wigStack [2] has been proposed. The method avoids generating large intermediate results which do not contribute to the final answer and is CPU and I/O optimal when twig patterns only have ancestor-descendant relationships. Another important direction of XML query processing is to build structural indexes [3][8] [13][15] over XML documents to avoid unnecessary scanning of source documents. We regard XML structural indexing as a technique to partition XML documents and call it streaming scheme in our paper. In this paper we develop a method to perform holistic twig pattern matching on XML documents partitioned using various streaming schemes. Our method avoids unnecessary scanning of irrelevant portion of XML documents. More importantly, depending on different streaming schemes used, it can process a large class of twig patterns consisting of both ancestordescendant and parent-child relationships and avoid generating redundant intermediate results. Our experiments demonstrate the applicability and the performance advantages of our approach.