We consider the correspondence
between nilmanifolds and Lie algebras with rational basis, and we define spectral
sequences converging to the respective cohomologies. The E2 terms of the spectral
sequences are the cohomolgies of isomorphic graded Lie algebras.
Each nilmanifold gives rise to a Lie algebra with rational basis. We give an
example which illustrates that not all such Lie algebras correspond to nilmanifolds.
Given a Lie algebra with rational basis we give a construction that produces a
nilmanifold with Lie algebra that is rationally equivalent to the starting Lie
algebra.