“…Spin manifolds and Spin bordism There has been a continuing interest in Spin manifolds, for a number of reasons to be discussed here, since the work of Atiyah and Singer on the index of elliptic operators beginning in the early 1960s. If M n is a Spin manifold, assumed to be Riemannian, then in addition to the bundle FM ->• M of oriented orthonormal frames (with structure group 80 (21)), one has a bundle FM->M with structure group Spin(2Z) defining the Spin-structure on M, FM-+FM being a double cover. Making use of Clifford algebras [9], one has the complex half-spin representations S+ and S~ of Spin(2Z), and so also corresponding vector bundles, which we still write as S + and S~.…”