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C_simp : tactic unit
`[simp only [C_0, C_1, C_neg, C_add, C_sub, C_mul, C_pow]]
def
C_simp
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
weierstrass_curve (R : Type u)
(a₁ a₂ a₃ a₄ a₆ : R)
structure
weierstrass_curve
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
A Weierstrass curve $Y^2 + a_1XY + a_3Y = X^3 + a_2X^2 + a_4X + a_6$ with parameters $a_i$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
b₂ : R
W.a₁ ^ 2 + 4 * W.a₂
def
weierstrass_curve.b₂
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `b₂` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
b₄ : R
2 * W.a₄ + W.a₁ * W.a₃
def
weierstrass_curve.b₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `b₄` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
b₆ : R
W.a₃ ^ 2 + 4 * W.a₆
def
weierstrass_curve.b₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `b₆` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
b₈ : R
W.a₁ ^ 2 * W.a₆ + 4 * W.a₂ * W.a₆ - W.a₁ * W.a₃ * W.a₄ + W.a₂ * W.a₃ ^ 2 - W.a₄ ^ 2
def
weierstrass_curve.b₈
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `b₈` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
b_relation : 4 * W.b₈ = W.b₂ * W.b₆ - W.b₄ ^ 2
by { simp only [b₂, b₄, b₆, b₈], ring1 }
lemma
weierstrass_curve.b_relation
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
c₄ : R
W.b₂ ^ 2 - 24 * W.b₄
def
weierstrass_curve.c₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `c₄` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
c₆ : R
-W.b₂ ^ 3 + 36 * W.b₂ * W.b₄ - 216 * W.b₆
def
weierstrass_curve.c₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The `c₆` coefficient of a Weierstrass curve.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Δ : R
-W.b₂ ^ 2 * W.b₈ - 8 * W.b₄ ^ 3 - 27 * W.b₆ ^ 2 + 9 * W.b₂ * W.b₄ * W.b₆
def
weierstrass_curve.Δ
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The discriminant `Δ` of a Weierstrass curve. If `R` is a field, then this polynomial vanishes if and only if the cubic curve cut out by this equation is singular. Sometimes only defined up to sign in the literature; we choose the sign used by the LMFDB. For more discussion, see [the LMFDB page on discriminants](https:/...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
c_relation : 1728 * W.Δ = W.c₄ ^ 3 - W.c₆ ^ 2
by { simp only [b₂, b₄, b₆, b₈, c₄, c₆, Δ], ring1 }
lemma
weierstrass_curve.c_relation
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change : weierstrass_curve R
{ a₁ := ↑u⁻¹ * (W.a₁ + 2 * s), a₂ := ↑u⁻¹ ^ 2 * (W.a₂ - s * W.a₁ + 3 * r - s ^ 2), a₃ := ↑u⁻¹ ^ 3 * (W.a₃ + r * W.a₁ + 2 * t), a₄ := ↑u⁻¹ ^ 4 * (W.a₄ - s * W.a₃ + 2 * r * W.a₂ - (t + r * s) * W.a₁ + 3 * r ^ 2 - 2 * s * t), a₆ := ↑u⁻¹ ^ 6 * (W.a₆ + r * W.a₄ + r ^ 2 * W.a₂ + r ^ 3 - t * W.a₃ - t ^ 2 - r * t * W.a...
def
weierstrass_curve.variable_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "weierstrass_curve" ]
The Weierstrass curve over `R` induced by an admissible linear change of variables $(X, Y) \mapsto (u^2X + r, u^3Y + u^2sX + t)$ for some $u \in R^\times$ and some $r, s, t \in R$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_b₂ : (W.variable_change u r s t).b₂ = ↑u⁻¹ ^ 2 * (W.b₂ + 12 * r)
by { simp only [b₂, variable_change_a₁, variable_change_a₂], ring1 }
lemma
weierstrass_curve.variable_change_b₂
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_b₄ : (W.variable_change u r s t).b₄ = ↑u⁻¹ ^ 4 * (W.b₄ + r * W.b₂ + 6 * r ^ 2)
by { simp only [b₂, b₄, variable_change_a₁, variable_change_a₃, variable_change_a₄], ring1 }
lemma
weierstrass_curve.variable_change_b₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_b₆ : (W.variable_change u r s t).b₆ = ↑u⁻¹ ^ 6 * (W.b₆ + 2 * r * W.b₄ + r ^ 2 * W.b₂ + 4 * r ^ 3)
by { simp only [b₂, b₄, b₆, variable_change_a₃, variable_change_a₆], ring1 }
lemma
weierstrass_curve.variable_change_b₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_b₈ : (W.variable_change u r s t).b₈ = ↑u⁻¹ ^ 8 * (W.b₈ + 3 * r * W.b₆ + 3 * r ^ 2 * W.b₄ + r ^ 3 * W.b₂ + 3 * r ^ 4)
by { simp only [b₂, b₄, b₆, b₈, variable_change_a₁, variable_change_a₂, variable_change_a₃, variable_change_a₄, variable_change_a₆], ring1 }
lemma
weierstrass_curve.variable_change_b₈
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_c₄ : (W.variable_change u r s t).c₄ = ↑u⁻¹ ^ 4 * W.c₄
by { simp only [c₄, variable_change_b₂, variable_change_b₄], ring1 }
lemma
weierstrass_curve.variable_change_c₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_c₆ : (W.variable_change u r s t).c₆ = ↑u⁻¹ ^ 6 * W.c₆
by { simp only [c₆, variable_change_b₂, variable_change_b₄, variable_change_b₆], ring1 }
lemma
weierstrass_curve.variable_change_c₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_Δ : (W.variable_change u r s t).Δ = ↑u⁻¹ ^ 12 * W.Δ
by { dsimp, ring1 }
lemma
weierstrass_curve.variable_change_Δ
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change : weierstrass_curve A
⟨algebra_map R A W.a₁, algebra_map R A W.a₂, algebra_map R A W.a₃, algebra_map R A W.a₄, algebra_map R A W.a₆⟩
def
weierstrass_curve.base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "weierstrass_curve" ]
The Weierstrass curve over `R` base changed to `A`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_b₂ : (W.base_change A).b₂ = algebra_map R A W.b₂
by { simp only [b₂, base_change_a₁, base_change_a₂], map_simp }
lemma
weierstrass_curve.base_change_b₂
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_b₄ : (W.base_change A).b₄ = algebra_map R A W.b₄
by { simp only [b₄, base_change_a₁, base_change_a₃, base_change_a₄], map_simp }
lemma
weierstrass_curve.base_change_b₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_b₆ : (W.base_change A).b₆ = algebra_map R A W.b₆
by { simp only [b₆, base_change_a₃, base_change_a₆], map_simp }
lemma
weierstrass_curve.base_change_b₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_b₈ : (W.base_change A).b₈ = algebra_map R A W.b₈
by { simp only [b₈, base_change_a₁, base_change_a₂, base_change_a₃, base_change_a₄, base_change_a₆], map_simp }
lemma
weierstrass_curve.base_change_b₈
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_c₄ : (W.base_change A).c₄ = algebra_map R A W.c₄
by { simp only [c₄, base_change_b₂, base_change_b₄], map_simp }
lemma
weierstrass_curve.base_change_c₄
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_c₆ : (W.base_change A).c₆ = algebra_map R A W.c₆
by { simp only [c₆, base_change_b₂, base_change_b₄, base_change_b₆], map_simp }
lemma
weierstrass_curve.base_change_c₆
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_Δ : (W.base_change A).Δ = algebra_map R A W.Δ
by { simp only [Δ, base_change_b₂, base_change_b₄, base_change_b₆, base_change_b₈], map_simp }
lemma
weierstrass_curve.base_change_Δ
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_self : W.base_change R = W
by ext; refl
lemma
weierstrass_curve.base_change_self
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change_base_change : (W.base_change A).base_change B = W.base_change B
by ext; exact (is_scalar_tower.algebra_map_apply R A B _).symm
lemma
weierstrass_curve.base_change_base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "is_scalar_tower.algebra_map_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_torsion_polynomial : cubic R
⟨4, W.b₂, 2 * W.b₄, W.b₆⟩
def
weierstrass_curve.two_torsion_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic" ]
A cubic polynomial whose discriminant is a multiple of the Weierstrass curve discriminant. If `W` is an elliptic curve over a field `R` of characteristic different from 2, then its roots over a splitting field of `R` are precisely the $X$-coordinates of the non-zero 2-torsion points of `W`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_torsion_polynomial_disc : W.two_torsion_polynomial.disc = 16 * W.Δ
by { dsimp [two_torsion_polynomial, cubic.disc], ring1 }
lemma
weierstrass_curve.two_torsion_polynomial_disc
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic.disc" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_torsion_polynomial_disc_is_unit [invertible (2 : R)] : is_unit W.two_torsion_polynomial.disc ↔ is_unit W.Δ
begin rw [two_torsion_polynomial_disc, is_unit.mul_iff, show (16 : R) = 2 ^ 4, by norm_num1], exact and_iff_right (is_unit_of_invertible $ 2 ^ 4) end
lemma
weierstrass_curve.two_torsion_polynomial_disc_is_unit
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "invertible", "is_unit", "is_unit.mul_iff", "is_unit_of_invertible" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_torsion_polynomial_disc_ne_zero [nontrivial R] [invertible (2 : R)] (hΔ : is_unit W.Δ) : W.two_torsion_polynomial.disc ≠ 0
(W.two_torsion_polynomial_disc_is_unit.mpr hΔ).ne_zero
lemma
weierstrass_curve.two_torsion_polynomial_disc_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "invertible", "is_unit", "ne_zero", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial : R[X][Y]
Y ^ 2 + C (C W.a₁ * X + C W.a₃) * Y - C (X ^ 3 + C W.a₂ * X ^ 2 + C W.a₄ * X + C W.a₆)
def
weierstrass_curve.polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "polynomial" ]
The polynomial $W(X, Y) := Y^2 + a_1XY + a_3Y - (X^3 + a_2X^2 + a_4X + a_6)$ associated to a Weierstrass curve `W` over `R`. For ease of polynomial manipulation, this is represented as a term of type `R[X][X]`, where the inner variable represents $X$ and the outer variable represents $Y$. For clarity, the alternative n...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_eq : W.polynomial = cubic.to_poly ⟨0, 1, cubic.to_poly ⟨0, 0, W.a₁, W.a₃⟩, cubic.to_poly ⟨-1, -W.a₂, -W.a₄, -W.a₆⟩⟩
by { simp only [weierstrass_curve.polynomial, cubic.to_poly], C_simp, ring1 }
lemma
weierstrass_curve.polynomial_eq
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "C_simp", "cubic.to_poly", "weierstrass_curve.polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_ne_zero [nontrivial R] : W.polynomial ≠ 0
by { rw [polynomial_eq], exact cubic.ne_zero_of_b_ne_zero one_ne_zero }
lemma
weierstrass_curve.polynomial_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic.ne_zero_of_b_ne_zero", "nontrivial", "one_ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
degree_polynomial [nontrivial R] : W.polynomial.degree = 2
by { rw [polynomial_eq], exact cubic.degree_of_b_ne_zero' one_ne_zero }
lemma
weierstrass_curve.degree_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic.degree_of_b_ne_zero'", "nontrivial", "one_ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nat_degree_polynomial [nontrivial R] : W.polynomial.nat_degree = 2
by { rw [polynomial_eq], exact cubic.nat_degree_of_b_ne_zero' one_ne_zero }
lemma
weierstrass_curve.nat_degree_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic.nat_degree_of_b_ne_zero'", "nontrivial", "one_ne_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monic_polynomial : W.polynomial.monic
by { nontriviality R, simpa only [polynomial_eq] using cubic.monic_of_b_eq_one' }
lemma
weierstrass_curve.monic_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "cubic.monic_of_b_eq_one'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
irreducible_polynomial [is_domain R] : irreducible W.polynomial
begin by_contra h, rcases (W.monic_polynomial.not_irreducible_iff_exists_add_mul_eq_coeff W.nat_degree_polynomial).mp h with ⟨f, g, h0, h1⟩, simp only [polynomial_eq, cubic.coeff_eq_c, cubic.coeff_eq_d] at h0 h1, apply_fun degree at h0 h1, rw [cubic.degree_of_a_ne_zero' $ neg_ne_zero.mpr $ one_ne_ze...
lemma
weierstrass_curve.irreducible_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "by_contra", "cubic.coeff_eq_c", "cubic.coeff_eq_d", "cubic.degree_of_a_ne_zero'", "cubic.degree_of_b_eq_zero'", "irreducible", "is_domain", "one_ne_zero'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial (x y : R) : (W.polynomial.eval $ C y).eval x = y ^ 2 + W.a₁ * x * y + W.a₃ * y - (x ^ 3 + W.a₂ * x ^ 2 + W.a₄ * x + W.a₆)
by { simp only [weierstrass_curve.polynomial], eval_simp, rw [add_mul, ← add_assoc] }
lemma
weierstrass_curve.eval_polynomial
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "eval_simp", "weierstrass_curve.polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial_zero : (W.polynomial.eval 0).eval 0 = -W.a₆
by simp only [← C_0, eval_polynomial, zero_add, zero_sub, mul_zero, zero_pow (nat.zero_lt_succ _)]
lemma
weierstrass_curve.eval_polynomial_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "mul_zero", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation (x y : R) : Prop
(W.polynomial.eval $ C y).eval x = 0
def
weierstrass_curve.equation
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The proposition that an affine point $(x, y)$ lies in `W`. In other words, $W(x, y) = 0$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_iff' (x y : R) : W.equation x y ↔ y ^ 2 + W.a₁ * x * y + W.a₃ * y - (x ^ 3 + W.a₂ * x ^ 2 + W.a₄ * x + W.a₆) = 0
by rw [equation, eval_polynomial]
lemma
weierstrass_curve.equation_iff'
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_iff (x y : R) : W.equation x y ↔ y ^ 2 + W.a₁ * x * y + W.a₃ * y = x ^ 3 + W.a₂ * x ^ 2 + W.a₄ * x + W.a₆
by rw [equation_iff', sub_eq_zero]
lemma
weierstrass_curve.equation_iff
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_zero : W.equation 0 0 ↔ W.a₆ = 0
by rw [equation, C_0, eval_polynomial_zero, neg_eq_zero]
lemma
weierstrass_curve.equation_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_iff_variable_change (x y : R) : W.equation x y ↔ (W.variable_change 1 x 0 y).equation 0 0
begin rw [equation_iff', ← neg_eq_zero, equation_zero, variable_change_a₆, inv_one, units.coe_one], congr' 2, ring1 end
lemma
weierstrass_curve.equation_iff_variable_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "inv_one", "units.coe_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_iff_base_change [nontrivial A] [no_zero_smul_divisors R A] (x y : R) : W.equation x y ↔ (W.base_change A).equation (algebra_map R A x) (algebra_map R A y)
begin simp only [equation_iff], refine ⟨λ h, _, λ h, _⟩, { convert congr_arg (algebra_map R A) h; { map_simp, refl } }, { apply no_zero_smul_divisors.algebra_map_injective R A, map_simp, exact h } end
lemma
weierstrass_curve.equation_iff_base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp", "no_zero_smul_divisors", "no_zero_smul_divisors.algebra_map_injective", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
equation_iff_base_change_of_base_change [nontrivial B] [no_zero_smul_divisors A B] (x y : A) : (W.base_change A).equation x y ↔ (W.base_change B).equation (algebra_map A B x) (algebra_map A B y)
by rw [equation_iff_base_change (W.base_change A) B, base_change_base_change]
lemma
weierstrass_curve.equation_iff_base_change_of_base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "no_zero_smul_divisors", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_X : R[X][Y]
C (C W.a₁) * Y - C (C 3 * X ^ 2 + C (2 * W.a₂) * X + C W.a₄)
def
weierstrass_curve.polynomial_X
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The partial derivative $W_X(X, Y)$ of $W(X, Y)$ with respect to $X$. TODO: define this in terms of `polynomial.derivative`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial_X (x y : R) : (W.polynomial_X.eval $ C y).eval x = W.a₁ * y - (3 * x ^ 2 + 2 * W.a₂ * x + W.a₄)
by { simp only [polynomial_X], eval_simp }
lemma
weierstrass_curve.eval_polynomial_X
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "eval_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial_X_zero : (W.polynomial_X.eval 0).eval 0 = -W.a₄
by simp only [← C_0, eval_polynomial_X, zero_add, zero_sub, mul_zero, zero_pow zero_lt_two]
lemma
weierstrass_curve.eval_polynomial_X_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "mul_zero", "zero_lt_two", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
polynomial_Y : R[X][Y]
C (C 2) * Y + C (C W.a₁ * X + C W.a₃)
def
weierstrass_curve.polynomial_Y
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The partial derivative $W_Y(X, Y)$ of $W(X, Y)$ with respect to $Y$. TODO: define this in terms of `polynomial.derivative`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial_Y (x y : R) : (W.polynomial_Y.eval $ C y).eval x = 2 * y + W.a₁ * x + W.a₃
by { simp only [polynomial_Y], eval_simp, rw [← add_assoc] }
lemma
weierstrass_curve.eval_polynomial_Y
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "eval_simp" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eval_polynomial_Y_zero : (W.polynomial_Y.eval 0).eval 0 = W.a₃
by simp only [← C_0, eval_polynomial_Y, zero_add, mul_zero]
lemma
weierstrass_curve.eval_polynomial_Y_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "mul_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular (x y : R) : Prop
W.equation x y ∧ ((W.polynomial_X.eval $ C y).eval x ≠ 0 ∨ (W.polynomial_Y.eval $ C y).eval x ≠ 0)
def
weierstrass_curve.nonsingular
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The proposition that an affine point $(x, y)$ on `W` is nonsingular. In other words, either $W_X(x, y) \ne 0$ or $W_Y(x, y) \ne 0$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_iff' (x y : R) : W.nonsingular x y ↔ W.equation x y ∧ (W.a₁ * y - (3 * x ^ 2 + 2 * W.a₂ * x + W.a₄) ≠ 0 ∨ 2 * y + W.a₁ * x + W.a₃ ≠ 0)
by rw [nonsingular, equation_iff', eval_polynomial_X, eval_polynomial_Y]
lemma
weierstrass_curve.nonsingular_iff'
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_iff (x y : R) : W.nonsingular x y ↔ W.equation x y ∧ (W.a₁ * y ≠ 3 * x ^ 2 + 2 * W.a₂ * x + W.a₄ ∨ y ≠ -y - W.a₁ * x - W.a₃)
by { rw [nonsingular_iff', sub_ne_zero, ← @sub_ne_zero _ _ y], congr' 4; ring1 }
lemma
weierstrass_curve.nonsingular_iff
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_zero : W.nonsingular 0 0 ↔ W.a₆ = 0 ∧ (W.a₃ ≠ 0 ∨ W.a₄ ≠ 0)
by rw [nonsingular, equation_zero, C_0, eval_polynomial_X_zero, neg_ne_zero, eval_polynomial_Y_zero, or_comm]
lemma
weierstrass_curve.nonsingular_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_iff_variable_change (x y : R) : W.nonsingular x y ↔ (W.variable_change 1 x 0 y).nonsingular 0 0
begin rw [nonsingular_iff', equation_iff_variable_change, equation_zero, ← neg_ne_zero, or_comm, nonsingular_zero, variable_change_a₃, variable_change_a₄, inv_one, units.coe_one], congr' 4; ring1 end
lemma
weierstrass_curve.nonsingular_iff_variable_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "inv_one", "units.coe_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_iff_base_change [nontrivial A] [no_zero_smul_divisors R A] (x y : R) : W.nonsingular x y ↔ (W.base_change A).nonsingular (algebra_map R A x) (algebra_map R A y)
begin rw [nonsingular_iff, nonsingular_iff, and_congr $ W.equation_iff_base_change A x y], refine ⟨or.imp (not_imp_not.mpr $ λ h, _) (not_imp_not.mpr $ λ h, _), or.imp (not_imp_not.mpr $ λ h, _) (not_imp_not.mpr $ λ h, _)⟩, any_goals { apply no_zero_smul_divisors.algebra_map_injective R A, map_simp, exact h }...
lemma
weierstrass_curve.nonsingular_iff_base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "map_simp", "no_zero_smul_divisors", "no_zero_smul_divisors.algebra_map_injective", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_iff_base_change_of_base_change [nontrivial B] [no_zero_smul_divisors A B] (x y : A) : (W.base_change A).nonsingular x y ↔ (W.base_change B).nonsingular (algebra_map A B x) (algebra_map A B y)
by rw [nonsingular_iff_base_change (W.base_change A) B, base_change_base_change]
lemma
weierstrass_curve.nonsingular_iff_base_change_of_base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "no_zero_smul_divisors", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_zero_of_Δ_ne_zero (h : W.equation 0 0) (hΔ : W.Δ ≠ 0) : W.nonsingular 0 0
by { simp only [equation_zero, nonsingular_zero] at *, contrapose! hΔ, simp [h, hΔ] }
lemma
weierstrass_curve.nonsingular_zero_of_Δ_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular_of_Δ_ne_zero {x y : R} (h : W.equation x y) (hΔ : W.Δ ≠ 0) : W.nonsingular x y
(W.nonsingular_iff_variable_change x y).mpr $ nonsingular_zero_of_Δ_ne_zero _ ((W.equation_iff_variable_change x y).mp h) $ by rwa [variable_change_Δ, inv_one, units.coe_one, one_pow, one_mul]
lemma
weierstrass_curve.nonsingular_of_Δ_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "inv_one", "one_mul", "one_pow", "units.coe_one" ]
A Weierstrass curve is nonsingular at every point if its discriminant is non-zero.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coordinate_ring : Type u
adjoin_root W.polynomial
def
weierstrass_curve.coordinate_ring
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root" ]
The coordinate ring $R[W] := R[X, Y] / \langle W(X, Y) \rangle$ of `W`. Note that `derive comm_ring` generates a reducible instance of `comm_ring` for `coordinate_ring`. In certain circumstances this might be extremely slow, because all instances in its definition are unified exponentially many times. In this case, on...
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
function_field : Type u
fraction_ring W.coordinate_ring
abbreviation
weierstrass_curve.function_field
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "fraction_ring", "function_field" ]
The function field $R(W) := \mathrm{Frac}(R[W])$ of `W`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_domain_of_field {F : Type u} [field F] (W : weierstrass_curve F) : is_domain W.coordinate_ring
by { classical, apply_instance }
instance
weierstrass_curve.coordinate_ring.is_domain_of_field
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "field", "is_domain", "weierstrass_curve" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_class : W.coordinate_ring
adjoin_root.mk W.polynomial $ C $ X - C x
def
weierstrass_curve.coordinate_ring.X_class
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk" ]
The class of the element $X - x$ in $R[W]$ for some $x \in R$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_class_ne_zero [nontrivial R] : X_class W x ≠ 0
adjoin_root.mk_ne_zero_of_nat_degree_lt W.monic_polynomial (C_ne_zero.mpr $ X_sub_C_ne_zero x) $ by { rw [nat_degree_polynomial, nat_degree_C], norm_num1 }
lemma
weierstrass_curve.coordinate_ring.X_class_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk_ne_zero_of_nat_degree_lt", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Y_class : W.coordinate_ring
adjoin_root.mk W.polynomial $ Y - C y
def
weierstrass_curve.coordinate_ring.Y_class
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk" ]
The class of the element $Y - y(X)$ in $R[W]$ for some $y(X) \in R[X]$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Y_class_ne_zero [nontrivial R] : Y_class W y ≠ 0
adjoin_root.mk_ne_zero_of_nat_degree_lt W.monic_polynomial (X_sub_C_ne_zero y) $ by { rw [nat_degree_polynomial, nat_degree_X_sub_C], norm_num1 }
lemma
weierstrass_curve.coordinate_ring.Y_class_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk_ne_zero_of_nat_degree_lt", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
X_ideal : ideal W.coordinate_ring
span {X_class W x}
def
weierstrass_curve.coordinate_ring.X_ideal
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "ideal" ]
The ideal $\langle X - x \rangle$ of $R[W]$ for some $x \in R$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Y_ideal : ideal W.coordinate_ring
span {Y_class W y}
def
weierstrass_curve.coordinate_ring.Y_ideal
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "ideal" ]
The ideal $\langle Y - y(X) \rangle$ of $R[W]$ for some $y(X) \in R[X]$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
XY_ideal (x : R) (y : R[X]) : ideal W.coordinate_ring
span {X_class W x, Y_class W y}
def
weierstrass_curve.coordinate_ring.XY_ideal
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "ideal" ]
The ideal $\langle X - x, Y - y(X) \rangle$ of $R[W]$ for some $x \in R$ and $y(X) \in R[X]$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
algebra' : algebra R W.coordinate_ring
quotient.algebra R
instance
weierstrass_curve.coordinate_ring.algebra'
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quotient_XY_ideal_equiv {x : R} {y : R[X]} (h : (W.polynomial.eval y).eval x = 0) : (W.coordinate_ring ⧸ XY_ideal W x y) ≃ₐ[R] R
(quotient_equiv_alg_of_eq R $ by simpa only [XY_ideal, X_class, Y_class, ← set.image_pair, ← map_span]).trans $ (double_quot.quot_quot_equiv_quot_of_leₐ R $ (span_singleton_le_iff_mem _).mpr $ mem_span_C_X_sub_C_X_sub_C_iff_eval_eval_eq_zero.mpr h).trans $ ((quotient_span_C_X_sub_C_alg_equiv (X - C x) y).re...
def
weierstrass_curve.coordinate_ring.quotient_XY_ideal_equiv
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "double_quot.quot_quot_equiv_quot_of_leₐ", "restrict_scalars", "set.image_pair" ]
The $R$-algebra isomorphism from $R[W] / \langle X - x, Y - y(X) \rangle$ to $R$ obtained by evaluation at $y(X)$ and at $x$ provided that $W(x, y(x)) = 0$.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
basis : basis (fin 2) R[X] W.coordinate_ring
(subsingleton_or_nontrivial R).by_cases (λ _, by exactI default) $ λ _, by exactI ((adjoin_root.power_basis' W.monic_polynomial).basis.reindex $ fin_congr W.nat_degree_polynomial)
def
weierstrass_curve.coordinate_ring.basis
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.power_basis'", "basis", "basis.reindex", "fin_congr", "subsingleton_or_nontrivial" ]
The basis $\{1, Y\}$ for the coordinate ring $R[W]$ over the polynomial ring $R[X]$. Given a Weierstrass curve `W`, write `W^.coordinate_ring.basis` for this basis.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
basis_apply (n : fin 2) : W^.coordinate_ring.basis n = (adjoin_root.power_basis' W.monic_polynomial).gen ^ (n : ℕ)
begin classical, nontriviality R, simpa only [coordinate_ring.basis, or.by_cases, dif_neg (not_subsingleton R), basis.reindex_apply, power_basis.basis_eq_pow] end
lemma
weierstrass_curve.coordinate_ring.basis_apply
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.power_basis'", "basis.reindex_apply", "not_subsingleton" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
basis_zero : W^.coordinate_ring.basis 0 = 1
by simpa only [basis_apply] using pow_zero _
lemma
weierstrass_curve.coordinate_ring.basis_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "pow_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
basis_one : W^.coordinate_ring.basis 1 = adjoin_root.mk W.polynomial Y
by simpa only [basis_apply] using pow_one _
lemma
weierstrass_curve.coordinate_ring.basis_one
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "pow_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_basis : (W^.coordinate_ring.basis : fin 2 → W.coordinate_ring) = ![1, adjoin_root.mk W.polynomial Y]
by { ext n, fin_cases n, exacts [basis_zero W, basis_one W] }
lemma
weierstrass_curve.coordinate_ring.coe_basis
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
smul (x : R[X]) (y : W.coordinate_ring) : x • y = adjoin_root.mk W.polynomial (C x) * y
(algebra_map_smul W.coordinate_ring x y).symm
lemma
weierstrass_curve.coordinate_ring.smul
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "algebra_map_smul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
smul_basis_eq_zero {p q : R[X]} (hpq : p • 1 + q • adjoin_root.mk W.polynomial Y = 0) : p = 0 ∧ q = 0
begin have h := fintype.linear_independent_iff.mp (coordinate_ring.basis W).linear_independent ![p, q], erw [fin.sum_univ_succ, basis_zero, fin.sum_univ_one, basis_one] at h, exact ⟨h hpq 0, h hpq 1⟩ end
lemma
weierstrass_curve.coordinate_ring.smul_basis_eq_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "linear_independent" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
exists_smul_basis_eq (x : W.coordinate_ring) : ∃ p q : R[X], p • 1 + q • adjoin_root.mk W.polynomial Y = x
begin have h := (coordinate_ring.basis W).sum_equiv_fun x, erw [fin.sum_univ_succ, fin.sum_univ_one, basis_zero, basis_one] at h, exact ⟨_, _, h⟩ end
lemma
weierstrass_curve.coordinate_ring.exists_smul_basis_eq
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
smul_basis_mul_C (p q : R[X]) : (p • 1 + q • adjoin_root.mk W.polynomial Y) * adjoin_root.mk W.polynomial (C y) = ((p * y) • 1 + (q * y) • adjoin_root.mk W.polynomial Y)
by { simp only [smul, _root_.map_mul], ring1 }
lemma
weierstrass_curve.coordinate_ring.smul_basis_mul_C
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
smul_basis_mul_Y (p q : R[X]) : (p • 1 + q • adjoin_root.mk W.polynomial Y) * adjoin_root.mk W.polynomial Y = (q * (X ^ 3 + C W.a₂ * X ^ 2 + C W.a₄ * X + C W.a₆)) • 1 + (p - q * (C W.a₁ * X + C W.a₃)) • adjoin_root.mk W.polynomial Y
begin have Y_sq : adjoin_root.mk W.polynomial Y ^ 2 = adjoin_root.mk W.polynomial (C (X ^ 3 + C W.a₂ * X ^ 2 + C W.a₄ * X + C W.a₆) - C (C W.a₁ * X + C W.a₃) * Y) := adjoin_root.mk_eq_mk.mpr ⟨1, by { simp only [weierstrass_curve.polynomial], ring1 }⟩, simp only [smul, add_mul, mul_assoc, ← sq, Y_sq, map_sub, ...
lemma
weierstrass_curve.coordinate_ring.smul_basis_mul_Y
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "mul_assoc", "weierstrass_curve.polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
norm_smul_basis (p q : R[X]) : algebra.norm R[X] (p • 1 + q • adjoin_root.mk W.polynomial Y) = p ^ 2 - p * q * (C W.a₁ * X + C W.a₃) - q ^ 2 * (X ^ 3 + C W.a₂ * X ^ 2 + C W.a₄ * X + C W.a₆)
begin simp_rw [algebra.norm_eq_matrix_det W^.coordinate_ring.basis, matrix.det_fin_two, algebra.left_mul_matrix_eq_repr_mul, basis_zero, mul_one, basis_one, smul_basis_mul_Y, map_add, finsupp.add_apply, map_smul, finsupp.smul_apply, ← basis_zero, ← basis_one, basis.repr_self_apply, if...
lemma
weierstrass_curve.coordinate_ring.norm_smul_basis
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "algebra.left_mul_matrix_eq_repr_mul", "algebra.norm", "algebra.norm_eq_matrix_det", "basis.repr_self_apply", "finsupp.add_apply", "finsupp.smul_apply", "matrix.det_fin_two", "mul_one", "one_ne_zero", "smul_eq_mul", "zero_ne_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_norm_smul_basis (p q : R[X]) : ↑(algebra.norm R[X] $ p • 1 + q • adjoin_root.mk W.polynomial Y) = adjoin_root.mk W.polynomial ((C p + C q * X) * (C p + C q * (-Y - C (C W.a₁ * X + C W.a₃))))
adjoin_root.mk_eq_mk.mpr ⟨C q ^ 2, by { rw [norm_smul_basis, weierstrass_curve.polynomial], C_simp, ring1 }⟩
lemma
weierstrass_curve.coordinate_ring.coe_norm_smul_basis
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "C_simp", "adjoin_root.mk", "algebra.norm", "weierstrass_curve.polynomial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
degree_norm_smul_basis [is_domain R] (p q : R[X]) : (algebra.norm R[X] $ p • 1 + q • adjoin_root.mk W.polynomial Y).degree = max (2 • p.degree) (2 • q.degree + 3)
begin have hdp : (p ^ 2).degree = 2 • p.degree := degree_pow p 2, have hdpq : (p * q * (C W.a₁ * X + C W.a₃)).degree ≤ p.degree + q.degree + 1, { simpa only [degree_mul] using add_le_add_left degree_linear_le (p.degree + q.degree) }, have hdq : (q ^ 2 * (X ^ 3 + C W.a₂ * X ^ 2 + C W.a₄ * X + C W.a₆)).degree = 2...
lemma
weierstrass_curve.coordinate_ring.degree_norm_smul_basis
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "adjoin_root.mk", "algebra.norm", "is_domain", "max_bot_left", "max_bot_right", "mul_zero", "one_mul", "one_ne_zero'", "zero_lt_two", "zero_mul", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
degree_norm_ne_one [is_domain R] (x : W.coordinate_ring) : (algebra.norm R[X] x).degree ≠ 1
begin rcases exists_smul_basis_eq x with ⟨p, q, rfl⟩, rw [degree_norm_smul_basis], rcases p.degree with (_ | _ | _ | _); cases q.degree, any_goals { rintro (_ | _) }, exact (lt_max_of_lt_right dec_trivial).ne' end
lemma
weierstrass_curve.coordinate_ring.degree_norm_ne_one
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra.norm", "is_domain", "lt_max_of_lt_right" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nat_degree_norm_ne_one [is_domain R] (x : W.coordinate_ring) : (algebra.norm R[X] x).nat_degree ≠ 1
mt (degree_eq_iff_nat_degree_eq_of_pos zero_lt_one).mpr $ degree_norm_ne_one x
lemma
weierstrass_curve.coordinate_ring.nat_degree_norm_ne_one
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra.norm", "is_domain", "zero_lt_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
elliptic_curve (R : Type u) [comm_ring R] extends weierstrass_curve R
(Δ' : Rˣ) (coe_Δ' : ↑Δ' = to_weierstrass_curve.Δ)
structure
elliptic_curve
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "comm_ring", "weierstrass_curve" ]
An elliptic curve over a commutative ring. Note that this definition is only mathematically accurate for certain rings whose Picard group has trivial 12-torsion, such as a field or a PID.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
j : R
↑E.Δ'⁻¹ * E.c₄ ^ 3
def
elliptic_curve.j
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[]
The j-invariant `j` of an elliptic curve, which is invariant under isomorphisms over `R`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_torsion_polynomial_disc_ne_zero [nontrivial R] [invertible (2 : R)] : E.two_torsion_polynomial.disc ≠ 0
E.two_torsion_polynomial_disc_ne_zero $ E.coe_Δ' ▸ E.Δ'.is_unit
lemma
elliptic_curve.two_torsion_polynomial_disc_ne_zero
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "invertible", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
nonsingular [nontrivial R] {x y : R} (h : E.equation x y) : E.nonsingular x y
E.nonsingular_of_Δ_ne_zero h $ E.coe_Δ' ▸ E.Δ'.ne_zero
lemma
elliptic_curve.nonsingular
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change : elliptic_curve R
⟨E.variable_change u r s t, u⁻¹ ^ 12 * E.Δ', by rw [units.coe_mul, units.coe_pow, coe_Δ', E.variable_change_Δ]⟩
def
elliptic_curve.variable_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "elliptic_curve", "units.coe_mul", "units.coe_pow" ]
The elliptic curve over `R` induced by an admissible linear change of variables $(X, Y) \mapsto (u^2X + r, u^3Y + u^2sX + t)$ for some $u \in R^\times$ and some $r, s, t \in R$. When `R` is a field, any two Weierstrass equations isomorphic to `E` are related by this.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_variable_change_Δ' : (↑(E.variable_change u r s t).Δ' : R) = ↑u⁻¹ ^ 12 * E.Δ'
by rw [variable_change_Δ', units.coe_mul, units.coe_pow]
lemma
elliptic_curve.coe_variable_change_Δ'
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "units.coe_mul", "units.coe_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_inv_variable_change_Δ' : (↑(E.variable_change u r s t).Δ'⁻¹ : R) = u ^ 12 * ↑E.Δ'⁻¹
by rw [variable_change_Δ', mul_inv, inv_pow, inv_inv, units.coe_mul, units.coe_pow]
lemma
elliptic_curve.coe_inv_variable_change_Δ'
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "inv_inv", "inv_pow", "mul_inv", "units.coe_mul", "units.coe_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
variable_change_j : (E.variable_change u r s t).j = E.j
begin rw [j, coe_inv_variable_change_Δ'], have hu : (u * ↑u⁻¹ : R) ^ 12 = 1 := by rw [u.mul_inv, one_pow], linear_combination E.j * hu with { normalization_tactic := `[dsimp, ring1] } end
lemma
elliptic_curve.variable_change_j
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "one_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
base_change : elliptic_curve A
⟨E.base_change A, units.map ↑(algebra_map R A) E.Δ', by rw [units.coe_map, ring_hom.coe_monoid_hom, coe_Δ', E.base_change_Δ]⟩
def
elliptic_curve.base_change
algebraic_geometry.elliptic_curve
src/algebraic_geometry/elliptic_curve/weierstrass.lean
[ "algebra.cubic_discriminant", "ring_theory.norm", "tactic.linear_combination" ]
[ "algebra_map", "elliptic_curve", "ring_hom.coe_monoid_hom", "units.coe_map", "units.map" ]
The elliptic curve over `R` base changed to `A`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83