On Geroch's Counterexample to the Algebraic Hopf Conjecture

Paul F. Klembeck
1976 Proceedings of the American Mathematical Society  
In this paper we present a simplified version of Geroch's counterexample to the algebraic Hopf conjecture which requires only a knowledge of the formal symmetries of Riemannian curvature tensors.
doi:10.2307/2041496 fatcat:3l4wa4rsxvgefixeiaq4zrez7e