English
For any subalgebra S ⊆ A, the subalgebra S.op is a subalgebra of the opposite ring Aᵐᵒᵖ.
Русский
Для любой подалгебры S ⊆ A, подалгебра S.op является подалгеброй над противоположным кольцом Aᵐᵒᵖ.
LaTeX
$$$ S^{\mathrm{op}} \\text{is a subalgebra of } A^{\mathrm{op}}. $$$
Lean4
/-- Pull a subalgebra back to an opposite subalgebra along `MulOpposite.unop` -/
@[simps! coe toSubsemiring]
protected def op (S : Subalgebra R A) : Subalgebra R Aᵐᵒᵖ
where
toSubsemiring := S.toSubsemiring.op
algebraMap_mem' := S.algebraMap_mem