Formal completions of Néron models for algebraic tori

Oleg Demchenko*, Alexander Gurevich, Xavier Xarles

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We calculate the formal group law that represents the completion of the Néron model for an algebraic torus over ℚ split in a tamely ramified abelian extension. To that end, we introduce an analogue of the fixed part of a formal group law with respect to a group action and give a method to compute its Honda p-types.

Original languageAmerican English
Pages (from-to)607-638
Number of pages32
JournalProceedings of the London Mathematical Society
Issue number3
StatePublished - May 2010
Externally publishedYes

Bibliographical note

Funding Information:
The first author wishes to thank JSPS for financial support and the Mathematical Institute of Tohoku University for its hospitality. The second author was partially supported by the Minerva Foundation through the Emmy Noether Institute, the Ministry of Absorption, Israel, and the grant 3-3578 from the Ministry of Science, Israel, and the Russian Foundation for Basic Research. The third author was partially supported by the grant MTM 2006-11391 from DGI.


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