The full odd-degree norm polynomial gives an absolutely irreducible double-cover equation. No squarefree-part substitution is made.
theorem
CCDN.odd_degree_double_cover_irreducible
{F : Type u_1}
[Field F]
(p : Polynomial F)
(hp : Odd p.natDegree)
:
Irreducible (Polynomial.X ^ 2 - Polynomial.C p)
For a polynomial p of odd degree over a field F, the double-cover polynomial Y ^ 2 - p is
irreducible in F[X][Y].
theorem
CCDN.double_cover_bivariateTotalDegree
{R : Type u_1}
[CommRing R]
(p : Polynomial R)
(hp : 2 ≤ p.natDegree)
:
For a polynomial p of degree at least 2, the double-cover polynomial Y ^ 2 - p has total
degree deg p.
theorem
CCDN.signedNormCurvePolynomial_totalDegree
(K : Type u_1)
[Field K]
[NumberField K]
(β : NumberField.RingOfIntegers K)
{ε : ℤ}
(hε : ε ≠ 0)
(hn : 2 ≤ Module.finrank ℚ K)
:
For [K : ℚ] ≥ 2 and ε ≠ 0, the signed norm-curve polynomial y ^ 2 - ε * N(x - β) has total
degree [K : ℚ].