The concept of approximation is one of the most fundamental in rough set theory. In this work we examine this basic notion as well as its extensions and modifications. The goal is to construct a parameterized approximation mechanism making it possible to develop multi-stage multi-level concept hierarchies that are capable of maintaining acceptable level of imprecision from input to output.
['Jan G. Bazan', 'Nguyen Hung Son', 'Andrzej Skowron', 'Marcin S. Szczuka']
A view on rough set concept approximations