Union of closed points of $\mathbb{A}^2_k = \operatorname{Spec}(k[x,y])$
96618
Any finite set of points in in the projective plane can be defined by two polynomials
35855
Closed form for an infinite product
36700
Quotient space of closed unit ball and the unit 2-sphere $S^2$
143586
Is $[0,1]$ a union of family of disjoint closed intervals?
147827
How to calculate $|\operatorname {SL}_2(\mathbb Z/N\mathbb Z)|$?
129732
What is $\operatorname{Aut}(\mathbb{Z}_2\oplus \mathbb{Z}_2)$?
99236
Interior of closure of an open set
76482
Closure of the set of degree $n$ polynomials with $n$ real roots
140756
Image of closed unit ball under a compact operator
81550
Linking two theorems: on algebraic closure and on minimal splitting field
146664
The union of two linearly independent subsets
117508
Prove that the closed unit ball of $L^2[a,b]$ is closed in $L^1[a,b]$
94825
Open set as a finite union of closed sets
55764
Algebraic closure of $\mathbb F_p$
10477
Finding the closure of A=$\mathbb Q \cap [0,1]$.
125962
The set $A'$ is closed in a $T_1$ space
143457
Is product of two closed sets closed?