English
For a subspace W of V, the dual copairing on W is nondegenerate.
Русский
Для подпространства W ⊆ V дуальное копарирование невырождено.
LaTeX
$$$W_{\\text{dualCopairing}}\\;\\text{Nondegenerate}$$$
Lean4
theorem dualCopairing_nondegenerate (W : Subspace K V₁) : W.dualCopairing.Nondegenerate :=
by
constructor
· rw [LinearMap.separatingLeft_iff_ker_eq_bot, dualCopairing_eq]
apply LinearEquiv.ker
· rintro ⟨x⟩
simp only [Quotient.quot_mk_eq_mk, dualCopairing_apply, Quotient.mk_eq_zero]
rw [← forall_mem_dualAnnihilator_apply_eq_zero_iff, SetLike.forall]
exact id