Stability of closed characteristics on symmetric compact convex   hypersurfaces in $\R^{2n}$
  In this article, let $\Sigma\subset\R^{2n}$ be a compact convex hypersurface which is symmetric with respect to the origin. We prove that if $\Sg$ carries finitely many geometrically distinct closed characteristics, then at least $n-1$ of them must be non-hyperbolic; if $\Sg$ carries exactly $n$ geometrically distinct closed characteristics, then at least two of them must be elliptic. 
Wei Wang