Nonzero orders of a function occur at only finitely many normalized places
ProvedOAI.PiExponent.FormalInterpolation.polynomialCurveOrder_support_finitealgebraic-geometryfunction-fieldsnumber-theoryopenai-pi-exponent-017
Let be a finitely generated field extension of transcendence degree one, and let . Among the normalized discrete places of that are trivial on (the type PolynomialCurvePlace), only finitely many places satisfy .
This is the standard finiteness of support for a principal divisor on a smooth projective model of a one-variable function field over an algebraically closed constant field. The zero function is assigned order zero at every place by the untop₀ convention, so its support is empty.
Preamble
import Definitions.Def_OAI_PiExponent_WeightedIdealCurveCriterion import Mathlib.RingTheory.Algebraic.Defs open scoped BigOperators open OAI.PiExponent.FormalInterpolation
Formal statement
theorem OAI.PiExponent.FormalInterpolation.polynomialCurveOrder_support_finite
{E : Type} [Field E] [Algebra Complex E]
[Algebra.EssFiniteType Complex E]
(htrdeg : Algebra.trdeg Complex E = 1) (f : E) :
Set.Finite {nu : PolynomialCurvePlace E | polynomialCurveOrder nu f ≠ 0} := by sorrySource
Standard fact for algebraic function fields of one variable (product formula / principal divisors have finite support). Used as the geometric core of OAI.PiExponent.FormalInterpolation.coordinateWeightedPole_support_finite on Prove2Me; cf. OpenAI PiExponent Geometry/CurveZeroPole and Dedekind HeightOneSpectrum.Support.finite in Mathlib.