English
Every two-sided ideal I induces an ideal in the ambient ring, preserving the underlying set; i.e., there is a canonical left-idealization I.asIdeal of a two-sided ideal I.
Русский
Каждому двустороннему идеалу I соответствует канонический левый идеал I.asIdeal, сохраняющий множество элементов, лежащих в I.
LaTeX
$$$I:\ TwoSidedIdeal(R) \to^{\text{monotone}}\mathrm{Ideal}(R)$ is the left-ideal correspondence with carrier equal to I.$$
Lean4
/-- Every two-sided ideal is also a left ideal. -/
def asIdeal : TwoSidedIdeal R →o Ideal R
where
toFun
I :=
{ carrier := I
add_mem' := I.add_mem
zero_mem' := I.zero_mem
smul_mem' := fun r x hx => I.mul_mem_left r x hx }
monotone' _ _ h _ h' := h h'