English
If P1 and P2 are nonsingular and not vertically aligned in the obstruction sense, then their sum is nonsingular, following from the negAdd formula.
Русский
Если P1 и P2 невырождены и не образуют вертикальную пару, то их сумма невырождена, следуя из формулы negAdd.
LaTeX
$$(WeierstrassCurve.Affine.nonsingular_negAdd ...).mpr (WeierstrassCurve.Affine.nonsingular_neg ...)$$
Lean4
theorem nonsingular_add {x₁ x₂ y₁ y₂ : F} (h₁ : W.Nonsingular x₁ y₁) (h₂ : W.Nonsingular x₂ y₂)
(hxy : ¬(x₁ = x₂ ∧ y₁ = W.negY x₂ y₂)) :
W.Nonsingular (W.addX x₁ x₂ <| W.slope x₁ x₂ y₁ y₂) (W.addY x₁ x₂ y₁ <| W.slope x₁ x₂ y₁ y₂) :=
(nonsingular_neg ..).mpr <| nonsingular_negAdd h₁ h₂ hxy