Why is the naive notion of a product ideal not necessarily additively closed?
58425
Defining the Product of Ideals
27766
Comaximal ideals in a commutative ring
113136
Generators of the ideal correspond to $d$-uple embedding
36150
Ideal in a ring of continuous functions
96787
Why is the arbitrary sum, but not the arbitrary intersection, of ideals an ideal?
151829
Why are maximal ideals prime?
11405
If a nonempty set of real numbers is open and closed, is it $\mathbb{R}$? Why/Why not?
34966
Is the product of closed subgroups in topological group closed?
126672
Product of principal ideals: $(a)\cdot (b) = (a b)$
20296
The ideal $I= \langle x,y \rangle\subset k[x,y]$ is not principal
87382
Non-invertible elements form an ideal
9204
Counterexamples to the avoidance lemma for arbitrary ideals
93681
Integral closure of $\mathbb{Z}$ in $\mathbb{C}$ is not finitely generated as a $\mathbb{Z}$-module?
99353
Topology on cartesian product and product topology.
99715
Proper ideal and units proof
117536
Why is the localization at a prime ideal a local ring?
114193
On the absolute norm of an ideal