Simple Compression Code Supporting Random Access and Fast String Matching

Given a sequence S of n symbols over some alphabet Σ, we develop a new compression method that is (i) very simple to implement; (ii) provides O(1) time random access to any symbol of the original sequence; (iii) allows efficient pattern matching over the compressed sequence. Our simplest solution uses at most 2h + o(h) bits of space, where h = n(H0(S) + 1), and H0(S) is the zeroth-order empirical entropy of S. We discuss a number of improvements and trade-offs over the basic method. The new method is applied to text compression. We also propose average case optimal string matching algorithms.

• Type: Conference
• Year: 2007
• Where: WEA
• Authors: Kimmo Fredriksson, Fedor Nikitin
• Keywords: Algorithms, Compressed Sequence, Time Random Access, WEA 2007, Zeroth-order Empirical Entropy