Compressing and Randomly Accessing Sequences (note)

In this paper we consider the problem of storing sequences of symbols in a compressed format, while supporting random access to the symbols without decompression. Although this is a well-studied problem when the data is textual, the kind of sequences we look at are not textual, and we argue that traditional compression methods used in the text algorithms community (such as compressors targeting k-th order empirical entropy) do not perform as well on these sequential data, and simpler methods such as Huffman-coding the deltas between sequence elements give better compression performance. We discuss data structures that allow random access to sequence elements that target such measures.