I understand that compression methods may be split into two main sets:
The first set works regardless of the data being processed, i.e., they do not rely on any characteristic of the data, and thus need not to perform any preprocessing on any part of the dataset (before the compression itself). On the other hand, local methods analyze the data, extracting information that usually improves the compression rate.
While reading about some of these methods, I noticed that the unary method is not universal, which surprised me since I thought "globality" and "universality" referred to the same thing. The unary method does not rely on characteristics of the data to yield its encoding (i.e., it is a global method), and therefore it should be global/universal, shouldn't it?
My primary questions:
- What is the difference between universal and global methods?
- Aren't these classifications synonyms?