1) Number theory 
In number theory and combinatorics, a multipartition of a positive integer n is a way of writing n as a sum, each element of which is in turn a partition. The concept is also found in the theory of Lie algebras. An r-component multipartition of an integer n is an r-tuple of partitions λ(1),...,λ(r) where each λ(i) is a partition of some ai and ...