English
A nondegenerate form arises from a basis with no self-orthogonal elements and an orthogonality property.
Русский
Невырожденная форма порождается базисом без самоперекрестной ортогональности и соответствующим свойством ортогональности.
LaTeX
$$nondegenerate_of_not_isOrtho_basis_self$$
Lean4
/-- Given an orthogonal basis with respect to a bilinear map, the bilinear map is nondegenerate
if the basis has no elements which are self-orthogonal. -/
theorem nondegenerate_of_not_isOrtho_basis_self [NoZeroSMulDivisors R M₁] {B : M →ₗ[R] M →ₗ[R] M₁} (v : Basis n R M)
(hO : B.IsOrthoᵢ v) (h : ∀ i, ¬B.IsOrtho (v i) (v i)) : B.Nondegenerate :=
⟨IsOrthoᵢ.separatingLeft_of_not_isOrtho_basis_self v hO h, IsOrthoᵢ.separatingRight_iff_not_isOrtho_basis_self v hO h⟩