41. The computer-implemented method of claim 36 , further comprising: defining a block of dictionary data symbols; selecting every M th symbol from the defined block of dictionary data symbols and identifying its corresponding location in the dictionary; calculating a hash value HV M for each selected M th symbol; and storing the calculated hash value HV M and the corresponding dictionary location as an entry in the dictionary-index, wherein M≠N.
42. The computer-implemented method of claim 41 , wherein N and M do not have a common factor value.