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TauCeti.AlgebraicGeometry.EllipticCurve.Valuation

Valuations of Weierstrass invariants #

This file records how additive valuations of Weierstrass-curve invariants behave under admissible changes of variables.

Main results #

theorem WeierstrassCurve.ord_Δ_smul {K : Type u_1} [Field K] (w : Valuation K (WithZero (Multiplicative ℤ))) (C : VariableChange K) (W : WeierstrassCurve K) [W.IsElliptic] :
w.ord (C • W).Δ = w.ord W.Δ - 12 * w.ord ↑C.u

A change of variables subtracts twelve times the order of its scaling parameter from the order of the discriminant. This is a statement about an arbitrary ℤᵐ⁰-valued valuation of K; the discrete valuation of a local minimal model plays no role.