Is D1 — card le four of one three negative

import Mathlib.Algebra.Polynomial.Monic
import Mathlib.Algebra.QuadraticAlgebra.Basic
import Mathlib.Algebra.Ring.Basic
import Mathlib.Algebra.Ring.Equiv
import Mathlib.Algebra.Squarefree.Basic
import Mathlib.Analysis.Complex.Norm
import Mathlib.Data.Finset.Card
import Mathlib.Data.Fintype.EquivFin
import Mathlib.Data.Int.GCD
import Mathlib.Data.Int.Sqrt
import Mathlib.LinearAlgebra.Dimension.Free
import Mathlib.NumberTheory.NumberField.InfinitePlace.TotallyRealComplex
import Mathlib.NumberTheory.NumberField.Norm
import Mathlib.Tactic.IntervalCases
import Mathlib.Tactic.Linarith
import Mathlib.Tactic.LinearCombination
import Definitions.Def_D1Bound5_IsD1

section
open scoped NumberField
open Module

namespace D1Bound5




























theorem _root_.D1Bound5.IsD1.card_le_four_of_one_three_negative
    {K : Type*} [Field K] [NumberField K] [NumberField.IsTotallyComplex K]
    (hK : finrank ℚ K = 2) {A : Finset (𝓞 K)} (hA : IsD1 A)
    (h1 : (1 : 𝓞 K) ∈ A) (h3 : (3 : 𝓞 K) ∈ A)
    (hn : ∃ n : ℤ, n<0 ∧ (n : 𝓞 K) ∈ A) : A.card ≤ 4 := by sorry



end D1Bound5
end