Why is $\Bbb Q$ not $G_{\delta}$?
4518
How would one go about proving that the rationals are not the countable intersection of open sets?
58416
Valuations on $\Bbb Q(t)$
43462
Disprove $\mathcal{P}(A\Delta B) \setminus \{\emptyset\} = \mathcal{P}(A) \Delta\mathcal{P}(B) $. Is my proof good?
55713
Dirac delta in polar coordinates
58009
How to show that $\mathbb Q(\sqrt 2)$ is not field isomorphic to $\mathbb Q(\sqrt 3).$
116513
Distributional Laplacian of logarithm and the Dirac delta distribution
4552
Choice of $q$ in Baby Rudin's Example 1.1
94933
Levi civita and kronecker delta properties?
135092
How exactly can't $\delta$ depend on $x$ in the definition of uniform continuity?
67383
Prove that $G'$ is not planar.
119330
Dirac delta function and volume charge density
53331
$\mathbb{Q}(\sqrt2, \sqrt3)$ is not isomorphic to $\mathbb{Q}(\sqrt[4]2)$
128711
$(\Bbb Z\oplus \Bbb Z)[X] \not\cong \Bbb Z[X]\oplus \Bbb Z[X]\,$?
76900
$\Bbb Q$-linear is equivalent to additive
77957
How is $\mathbb N$ actually defined?
68144
How far can one get in analysis without leaving $\mathbb{Q}$?
126927
$\mathbb Q$ is not the direct product of two non-trivial groups.