Interest in partitions appeared in the 17th century when G. W. Leibniz (1669) investigated the number of ways a given positive integer can be decomposed into a sum of smaller integers. Later, L. Euler (1740) also used partitions in his work. But extensive investigation of partitions began in the 20th century with the works of S. Ramanujan (1917) and G. H. Hardy. In particular G. H. Hardy (1920) introduced the notations and to represent the two most commonly used types of parititions.
