On S.L. Tabachnikov's conjecture
  S. L. Tabachnikov's conjecture is proved: for any closed curve $\Gamma$ lying inside convex closed curve $\Gamma_1$ the mean absolute curvature $T(\Gamma)$ exceeds $T(\Gamma_1)$ if $\Gamma\ne k\Gamma_1$. An inequality $T(\Gamma)\ge T(\Gamma_1)$ is proved for curves in a hemisphere. 
A.I. Nazarov, F.V. Petrov