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TauCeti.RingTheory.Adjoin.Unit

Algebra generated by an integral unit #

This file records that over an Artinian commutative ring, the inverse of an integral unit belongs to the algebra generated by that unit. The proof uses Mathlib's IsArtinianRing.isUnit_of_isIntegral_of_nonZeroDivisor in the generated subalgebra.

Main declarations #

theorem TauCeti.Units.coe_inv_mem_adjoin {K : Type u} {A : Type v} [CommRing K] [IsArtinianRing K] [Ring A] [Algebra K A] (u : Aˣ) (hu : IsIntegral K ↑u) :
↑u⁻¹ ∈ K[↑u]

The inverse of an integral unit over an Artinian commutative ring belongs to the algebra generated by that unit.