 Schur functors are indexed by Young diagrams in such a way that the horizontal diagram with "n" cells corresponds to the "n"th exterior power functor, and the vertical diagram with "n" cells corresponds to the "n"th symmetric power functor.If a vector space "V" is a representation of a group "G", then formula_1 also has a natural action of "G" for any Schur functor formula_2.Schur functors are indexed by partitions and are described as follows.