Prove that $ \ A \ $ is a $ \ G_\delta \ $ subset of $ \ X \ $.
66630
Proof of Mazurkiewicz theorem
26658
A proof for $\nabla |u|^p = p\ \text{sgn}(u)|u|^{p-1}\nabla u$.
3599
show that if ${a_n} \to a$, and $a>0$, then $\exists N$ such that $a_n>0$ for $n \ge N$.
94469
How to prove that $|HK| = \dfrac{|H| \; |K|}{|H \cap K|}$?
118138
$\epsilon - \delta$ proof that $\lim_{x \to a} \sqrt x = \sqrt a$
144266
set theory proof of $A\cap B = A \setminus(A\setminus B)$
151493
Using $\epsilon$-$\delta$ to show a property of a function
9268
Proving that the Union of Two Compact Sets is Compact
102529
Prove that the set $\left\{ x, Ax, \dots, A^{k-1} x \right\}$ is linearly independent
47680
Prove that the union of the interior of a set and the boundary of the set is the closure of the set
143105
Show that, for every real number a, the set {$x ∈ S | f(x) ≤ a$} is a closed subset of $\mathbb R^d$
111515
Proving that $-a=(-1)\cdot a$
100387
Using $\epsilon-\delta$ to prove that a limit is not a specific number
144372
How to Prove that if $A$ is bounded, then $A \cdot A$ is bounded?
11710
How to show that $\mathbb{Q}$ is not $G_\delta$
83183
Why is $\langle x| x' \rangle=\delta(x-x')$?
83204
Is every $G_\delta$ set the set of continuity points of some function $f$?