Show that the set of products need not be an ideal
117590
Let I and J be ideals of a ring R. Show by example that the set of products {xy | x ∈ I, y ∈ J} need not be an ideal
72185
The negation of a limit condition, Spivak style.
119312
Product and Box Topologies
95373
Additive set function on a semiring of sets
47639
Uncountable Cartesian product of closed interval
84780
Cartesian products as sets of all functions.
150143
Convergence in measure of products
56440
Cartesian products and families
143457
Is product of two closed sets closed?
36485
$H_n(X,A) \not \approx \tilde{H}_n(X/A)$
3896
A closed set in $(A, \mathcal T_A)$ that is not closed in $(X, \mathcal T)$
134049
Showing an inequality is valid
43109
If a product is normal, are all of its partial products also normal?
84890
Extremising a functional with conditions
90816
Why does the product topology allow proper subsets for only finitely many elements?
74546
Negating A Mathematical Statement
17461
Show that a set is dense in $[-1,1]$