Statistics on Hilbert's Sixteenth Problem

Abstract

We study the statistics of the number of connected components and the volume of a random real algebraic hypersurface in RP^n defined by a Real Bombieri-Weyl distributed homogeneous polynomial of degree d. We prove that the expectation of the number of connected components of such hypersurface has order d^n, the asymptotic being in d for n fixed. We do not restrict ourselves to the random homogeneous case and we consider more generally random polynomials belonging to a window of eigenspaces of the laplacian on the sphere S^n, proving that the same asymptotic holds. As for the volume, we prove its expectation is of order d. Both these behaviors exhibit expectation of maximal order in light of Milnor's bound and the a priori bound for the volume.