LZ78 compression

A substitutional compression scheme which works by entering

phrases into a dictionary and then, when a reoccurrence of

that particular phrase is found, outputting the dictionary

index instead of the phrase. Several algorithms are based

on this principle, differing mainly in the manner in which

they manage the dictionary.

The most well-known Lempel-Ziv scheme is Terry Welch's

Lempel-Ziv Welch variant of LZ78.

[comp.compression FAQ].