Nonlinear Evolution of the Genus Statistics with Zel'dovich   Approximation
  Evolution of genus density is calculated from Gaussian initial conditions using Zel'dovich approximation. A new approach is introduced which formulates the desired quantity in a rotationally invariant manner. It is shown that normalized genus density does not depend on the initial spectral shape but is a function of the fluctuation amplitude only. 
Naoki Seto, Jun'ichi Yokoyama, Takahiko Matsubara, Masaru Siino