On the number of components of a complete intersection of real quadrics

Abstract

Our main results concern complete intersections of three real quadrics. We prove that the maximal number B0 2 (N) of connected components that a regular complete intersection of three real quadrics in ℙN may have differs at most by one from the maximal number of ovals of the submaximal depth [(N −1)/2] of a real plane projective curve of degree d = N +1. As a consequence, we obtain a lower bound 1/4 N2 +O(N) and an upper bound 3/8 N2+O(N) for B0 2 (N). © Springer Science+Business Media, LLC 2012.