| Résume | The special fiber of a smooth model for a Shimura variety of Hodge type admits a Newton stratification and an Ekedahl-Oort stratification, in analogy to PEL-type Shimura varieties these are obtained from the classification of p-divisible groups with certain additional structures which are associated to points on the special fiber. A special role among the Newton strata plays the ``$\mu$-ordinary locus'', the generalization of the ordinary locus in moduli spaces of abelian varieties.
We will explain a group theoretic approach to compare the Newton and Ekedahl-Oort stratification, and use this method to generalize results of Wedhorn and Moonen on the $\mu$-ordinary locus for PEL-type Shimura varieties to the Hodge type case. In particular this proves that the $\mu$-ordinary locus is open and dense. |
