A Lower Bound on the Average Error of Vector Quantizers J. H. Conway(*) Department of Pure Mathematics and Mathematical Statistics University of Cambridge Cambridge, CB2 1SB, England N. J. A. Sloane(**) Mathematical Sciences Research Center AT&T Bell Laboratories Murray Hill, NJ 07974, USA ABSTRACT A lower bound is proposed for the mean squared error of an n-dimensional vector quantizer with a large number of output points. Although no formal proof has been found, a plausible geometrical argument is given for believing that the bound is correct. The new bound is analogous to the Rogers bound for packing spheres, the Coxeter-Few-Rogers bound for covering space with spheres, and the Coxeter-Boroczky bound for packing spherical caps. It is significantly stronger than Zador's sphere bound for quantizers. (*) Present address: Mathematics Department Princeton University, Princeton, NJ 08540 (**) Present address: Information Sciences Research AT&T Shannon Lab Florham Park, NJ 07932-0971 For the full version see http://www.research.att.com/~njas/doc/low.pdf (pdf) or http://www.research.att.com/~njas/doc/low.ps (ps) For the figures see the files http://www.research.att.com/~njas/doc/lowfig1.JPG http://www.research.att.com/~njas/doc/lowfig2.JPG http://www.research.att.com/~njas/doc/lowfig3.JPG This paper was published (in a somewhat different form) in IEEE Trans. Information Theory, 31 (1985), 106-109.