PolynomialCurvePlace order support is finite given HasPrincipalDivisors
ProvedOAI.PiExponent.FormalInterpolation.polynomialCurveOrder_support_finite_of_hasPrincipalDivisorsfunction-fieldspi-exponentplaces
Assume admits principal divisors in the sense of AlgebraicCurve.HasPrincipalDivisors: for every nonzero the function on AlgebraicCurve.Place places is the evaluation of a finitely supported divisor.
Then, among the normalized discrete places of type PolynomialCurvePlace (integer-valued additive valuations trivial on and surjective onto ), only finitely many satisfy .
This is the comparison between the FormalInterpolation place type and the AlgebraicCurve place type: once principal divisors exist for the latter, the nonzero-order locus for the former is finite. 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 Definitions.Def_AlgebraicCurve_DivisorClassGroup open OAI.PiExponent.FormalInterpolation open AlgebraicCurve
Formal statement
theorem OAI.PiExponent.FormalInterpolation.polynomialCurveOrder_support_finite_of_hasPrincipalDivisors
{E : Type} [Field E] [Algebra Complex E]
[HasPrincipalDivisors Complex E] (f : E) :
Set.Finite {nu : PolynomialCurvePlace E | polynomialCurveOrder nu f ≠ 0} := by sorrySource
Bridge lemma for OAI.PiExponent.FormalInterpolation.polynomialCurveOrder_support_finite; compares PolynomialCurvePlace to AlgebraicCurve.Place under HasPrincipalDivisors (cf. AlgebraicCurve.finite_setOf_ord_ne_zero_of_finiteDimensional)