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. © 2009 London Mathematical Society.
Demchenko, O., Gurevich, A., & Xarles, X. (2010). Formal completions of Néron models for algebraic tori. Proceedings of the London Mathematical Society, 100, 607-638. https://doi.org/10.1112/plms/pdp039