Travaux de Kempf, Kleiman, Laksov sur les diviseurs exceptionnels
The diverse Dieudonné theories have as their common goal the classification of formal groups and -divisible groups. The most recent theory is Zink’s theory of displays. A display over a ring R is a finitely generated projective module over the ring of Witt vectors, , equipped with additional structures. Zink has shown that using this notion, more concrete than those previously defined, one can obtain a good theory and prove an equivalence theorem in great generality. I will give an overview of...
We discuss several additional properties a power linear Keller map may have. The Structural Conjecture of Drużkowski (1983) asserts that certain two such properties are equivalent, but we show that one of them is stronger than the other. We even show that the property of linear triangularizability is strictly in between. Furthermore, we give some positive results for small dimensions and small Jacobian ranks.
In answering questions of J. Maříková [Fund. Math. 209 (2010)] we prove a triangulation result that is of independent interest. In more detail, let R be an o-minimal field with a proper convex subring V, and let st: V → k be the corresponding standard part map. Under a mild assumption on (R,V) we show that a definable set X ⊆ Vⁿ admits a triangulation that induces a triangulation of its standard part st X ⊆ kⁿ.