English
A balance between duals and divisions: dual(J)/dual(I) = I/J; this expresses a cross-compatibility between taking duals and quotients.
Русский
Баланс дуалов и делений: dual(J)/dual(I) = I/J; это выражает совместимость операций дуализации и деления.
LaTeX
$$\frac{\mathrm{dual}_{A,K}(J)}{\mathrm{dual}_{A,K}(I)} = \frac{I}{J}$$
Lean4
@[simp]
theorem dual_dual : dual A K (dual A K I) = I :=
by
rw [dual_eq_mul_inv, dual_eq_mul_inv A K (I := I), mul_inv, inv_inv, ← mul_assoc, mul_inv_cancel₀, one_mul]
rw [dual_ne_zero_iff]
exact one_ne_zero