Gravity Formality
  We show that Willwacher's cyclic formality theorem can be extended to
preserve natural Gravity operations on cyclic multivector fields and cyclic
multidifferential operators. We express this in terms of a homotopy Gravity
quasi-isomorphism with explicit local formulas. For this, we develop operadic
tools related to mixed complexes and cyclic homology and prove that the operad
$\mathsf M_\circlearrowleft$ of natural operations on cyclic operators is
formal and hence quasi-isomorphic to the Gravity operad.
