1. Understanding the principle and method

The theory of Rough Sets is based on a mathematical concept developed by Z. Pawlak in the early 1980s, based on the theory of "rough" or "vague" sets. It involves processing "vague" or "imperfect" information in the context of decision support, in order to obtain object rankings.

This theory relies on the perceived differences between various objects to construct classes of objects that have no fundamental difference: this is the principle of indistinguishability.

The principle of Rough Sets theory is based on the limited information we have to distinguish between certain objects. A number of well-chosen objects are therefore used to identify their differences, or even to compare them.

In the course of its development, Rough Set theory has evolved thanks to various authors, introducing the notion of preference and...