∀ {R : Type u_1} [inst : CommRing R] {W' : WeierstrassCurve.Affine R} {x : R} {y : Polynomial R},
  (Ideal.map (Ideal.Quotient.mkₐ R (Ideal.span {W'.polynomial}))
      (Ideal.span {Polynomial.C (Polynomial.X - Polynomial.C x), Polynomial.X - Polynomial.C y})).IsTwoSided