Introduction to Set Theory

The ideas of empty-set infinity natural numbers had been the subjects of deep thought since the 5th century B.C with Greeks (Zeno of Elea 490 B.C-430 B.C) in the west and Indians in the east. So roots of the set theory are since antiquity. The concept of a set appears deceivingly simple at least to the trained mathematician but it isn''t so. The concept of set appeared only in the middle of the 19th century when mathematicians undertook to overcome problems that the notion of infinity posed since antiquity.