Data Compression : Searching for Patterns

a compression program doesn't have any concept of separate words : it only looks for patterns.

Pattern : combinaison of character that are repeated over the sentence

From simple pattern ( "ou" in "your" and "country" ) to more than one word ( "can do for you" )

The ability to rewrite the dictionary is the "adaptive" part of LZ adaptive dictionary-based algorithm.

The way a program actually does this is fairly complicated, as you can see by the discussions on
No matter what specific method you use, this in-depth searching system lets you compress the file much more efficiently than you could by just picking out words.

Using the patterns we picked out above, and adding "_" for spaces, we come up with this larger dictionary:

  1. ask_
  2. what_
  3. you
  4. r_country
  5. _can_do_for_you


Sentence 16 units + dictionary  40 units = 56 units!