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Isogeny classes for points of Shimura varieties with values in a finite field. (Isogenieklassen von Punkten von Shimuramannigfaltigkeiten mit Werten in einem endlichen Körper.) (German) Zbl 0604.14029
The article considers the Shimura variety associated to the moduli problem of classifying polarised abelian varieties with a compatible action of a semisimple algebra with positive involution. A suitable definition of CM-type (i.e. with compatibility with the action of the algebra) is introduced. The main result says that each point on the Shimura variety over a finite field is isogenous to a CM-object which can be lifted to a CM-object definable over a number field. Using this result one can then, following an idea of Langlands, to each isogeny class of points over a finite field associate a conjugacy class of the group of points over the rationals of the group associated to the Shimura variety. These results were earlier announced by Langlands and Rapoport with an apparently faulty proof. After some preliminary discussions of general type the proof reduces to a computation with Dieudonné modules.
Reviewer: T.Ekedahl

##### MSC:
 14K10 Algebraic moduli of abelian varieties, classification 14G15 Finite ground fields in algebraic geometry 14G35 Modular and Shimura varieties 14K22 Complex multiplication and abelian varieties 14L05 Formal groups, $$p$$-divisible groups
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##### References:
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