On the study of recompressing strings

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K16009
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Theory of informatics
• Research Institution: Kyushu Institute of Technology
• Principal Investigator: I Tomohiro 九州工業大学, 大学院情報工学研究院, 准教授 (20773360)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 文字列処理 / 可逆圧縮

Outline of Final Research Achievements

We studied the theory of compression to process huge string data. We obtained the following results: (1) We proposed a grammar compression method that works in optimal working space. (2) We showed how to answer longest common extension queries in grammar compressed strings (3) We proposed a practical algorithm to compute run-length encoded Burrows-Wheeler transform (RLBWT) in an online manner. (4) We showed how to compute Lempel-Ziv 77 via RLBWT in an online manner. (5) We proposed the first algorithm to compute RePair (the most notable grammar compression for its high compression performance) in compressed space.

Free Research Field

文字列処理

Academic Significance and Societal Importance of the Research Achievements

巨大データを解析・利用するために圧縮は欠かせない技術であり，様々な圧縮手法が提案されている．しかし，一般に圧縮手法には利点と欠点があるため，必要なデータ処理に応じて圧縮形式を変換する技術の発展が望まれる．本研究では，圧縮されたデータの利用価値を上げるために，圧縮形式間の効率的な変換技法を提案した．