Akademska digitalna zbirka SLovenije - logo
E-resources
Peer reviewed Open access
  • Ekedahl-Oort Strata for Goo...
    Zhang, Chao

    Canadian journal of mathematics, 04/2018, Volume: 70, Issue: 2
    Journal Article

    For a Shimura variety of Hodge type with hyperspecial level structure at a prime $p$ , Vasiu and Kisin constructed a smooth integral model (namely the integral canonical model) uniquely determined by a certain extension property. We define and study the Ekedahl-Oort stratifications on the special fibers of those integral canonical models when $p\,>\,2$ . This generalizes Ekedahl-Oort stratifications defined and studied by Oort on moduli spaces of principally polarized abelian varieties and those defined and studied by Moonen, Wedhorn, and Viehmann on good reductions of Shimura varieties of PEL type. We show that the Ekedahl-Oort strata are parameterized by certain elements $w$ in the Weyl group of the reductive group in the Shimura datum. We prove that the stratum corresponding to $w$ is smooth of dimension $l\left( w \right)$ (i.e., the length of $w$ ) if it is non-empty. We also determine the closure of each stratum.