On the Hopf algebra of a local ring

The Hopf algebra $\operatorname{Tor}^A(k, k)$, where $A$ is a local ring and $k$ its residue class field, is studied by means of the Eilenberg–Moore spectral sequence converging to it and to a quotient algebra. It is shown that the Poincaré series of $A$ depends only on the homology structure of its Koszul complex as an algebra with Massey operations.