Gromov's celebrated systolic inequality from '83 is a universal volume lower bound in terms of the least length of a noncontractible loop in M. His proof passes via a strongly isometric imbedding called the Kuratowski imbedding, into the Banach space of bounded functions on M. We show that the imbedding admits an approximation by a (1 + )-bi-Lipschitz (onto its image), finite-dimensional imbedding for every > 0, using the first variation formula and the mean value theorem.
Mathematics Subject Classification (2000)Primary 53C23 · Secondary 26E35
Metric imbeddings and Gromov's theoremIn '83, Gromov proved the systolic inequality for essential manifolds M. Namely, consider the least length (systole, denoted "sys") of a non-contractible loop in a closed Riemannian manifold M. Then the systole is bounded above in terms of the volume of M, if M satisfies the topological hypothesis of being essential (for instance, if π i (M) = 0 for i ≥ 2). See Guth [14] for a helpful overview.A key technique in Gromov's seminal text [11] is the Kuratowski imbedding. Thus, Gromov imbeds a Riemannian manifold M into the space