A normed vector space is said to be uniformly convex if for sequences , , the assumptions , , and together imply that
as tends to infinity.
Such spaces are important in functional analysis. For example, the classical Banach-Saks theorem can be generalized so that the desired conclusion holds in the case that is a Banach space whose conjugate space (that is, the complex conjugate of the dual vector space ) is uniformly convex.