Efficient Textual Web Retrieval using Wavelet Tree

摘要

Searching on the web is one of the most progressive and expanding field nowadays. A large amount of information is available on the World Wide Web, motivating the need of efficient text indexing method that support fast text retrieval. In the past, two main indexing techniques: Signature files and Inverted files have been proposed. First require much larger space to store index and are more expensive to construct and update than inverted files. Second has been efficiently implemented using different structures like Sorted array and B-Tree. Sorted array was very expensive in updating the indices while appending a new keyword and B-tree method breaks down if there are many words with the same prefix. This paper presents a modified index structure for text retrieval that keeps a good result to optimize the space needed to store and time to search document. The proposed index is designed using the Wavelet Tree (WT), which was originally designed as wavelet transform for images. Experimental results show that on increasing the query length, the WT based index performs better than others.