Modified LZW algorithm for efficient compressed text retrieval

With increasing amount of text data being stored in the compressed format, efficient information retrieval in the compressed domain has become a major concern. Being able to randomly access the compressed data is highly desirable for efficient retrieval and is required in many applications. For example, in a library information retrieval system, only the records that are relevant to the query are displayed. We present modified LZW algorithms that support fast random access to the compressed text. Instead of fully decompressing the text and outputting the results selectively, we allow random access and partial decoding of the compressed text and displaying the relevant portion. The compression ratio can also be improved using the modified LZW algorithm. Preliminary results on the time and storage performance are given.