NON-FORMAL HOMOGENEOUS SPACES

Abstract. Several large classes of homogeneous spaces are known to be formal—in the sense of Rational Homotopy Theory. However, it seems that far fewer examples of non-formal homogeneous spaces are known. In this article we provide several construction principles and charac-terisations for non-formal homogeneous spaces, which will yield a lot of examples. This will enable us to prove that, from dimension 72 on, such a space can be found in each dimension