“…Different versions of this statement have been discussed by Costello as well as Kontsevich, and a rough outline of a partial argument is present in [15], although there is no indication of the homotopy invariance there. A cognate of this theorem was proved at the level of rational homology in [4,5], relying on earlier work of Getzler [7,8]. This theorem is a nice improvement; using adjunctions along the lines of those in [18], one can see that the topological story implies the same result at the level of integral, not just rational, homology.…”