 Technically, let "M" be an essential Riemannian manifold of dimension "n"; denote by sys"π"1("M") the homotopy 1-systole of "M", that is, the least length of a non-contractible loop on "M".Then Gromov's inequality takes the form

where "C""n" is a universal constant only depending on the dimension of "M".A closed manifold is called "essential" if its fundamental class defines a nonzero element in the homology of its fundamental group, or more precisely in the homology of the corresponding Eilenberg–MacLane space.