Proposed hash table. Entries of proposed hash tables. Subsequence “AAAAA” is used as the key for storing the genome positions of “ACAAA” and “AAATA” because“AAAAA” is the center of the equivalence class that “ACAA” and“AAAT” belong to. The left hash table uses the center subsequence itself as a hash key. The right one uses the short code of the center subsequence as a hash key, where the short code is the information digits of the code. Short codes are described in Section Perfect Hamming Code.