Trace formula for component groups of Néron models
arXiv:0901.1809
Abstract
We study a trace formula for tamely ramified abelian varieties over a complete discretely valued field, which expresses the Euler characteristic of the special fiber of the Néron model of in terms of the Galois action on the -adic cohomology of . If has purely additive reduction, the trace formula yields a cohomological interpretation for the number of connected components of the special fiber of the Néron model.
Main result (Conjecture 1.1) proven unconditionally; Conjecture 1.2 in version 1 was recently proven by Liu and Lorenzini (see [10])