Rough Set Theory – Fundamentals and an Overview of its Main Applications

Rough Set Theory (RST) can be approached as an extension of the Classical Set Theory, for use when representing incomplete knowledge. Rough sets can be considered sets with fuzzy boundaries − sets that cannot be precisely characterized using the available set of attributes. The basic concept of the RST is the notion of approximation space, which is an ordered pair A=(U,R), where • U: nonempty set of objects, called universe • R: equivalence relation on U, called indiscernibility relation. [via]

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