@MatheinBoulomenos how much MRT do you know?

barely anything

I don't believe you :P

let f : A--> B be a surjective ring hom, then ideals of B are in 1-1 corresp with ideals of A that contain the kernel of f

@MatheinBoulomenos how useful is this in practice?

@MatheinBoulomenos Hi btw ^^

Hi @Jacksoja

quite useful

@MatheinBoulomenos it does apprear earliar in groups as well, noraml subgroups correp

But never seen it used yet, do you have a good example in mind ?

e.g. compute the ideals of $\Bbb C[X]/(X^2)$

the coordinate ring of "the thick point"

The composition $HK = \{h\circ k : h \in H \land k \in K\}$ of two subgroups $H,K$ to a group $G$ is a subgroup to $G$ only if $G$ is abelian, yes?

@Lozansky no

@LeakyNun Is abelian on $G$ sufficient but not necessary?

right