Is there a function $f : \mathbb Z \times \mathbb Z \to \mathbb Z$ that is one to one and onto?
6161
The cartesian product $\mathbb{N} \times \mathbb{N}$ is countable
61103
Prove that $\mathbb{|Q| = |Q\times Q|}$
35777
$\mathbb{R}[X,Y]/(Y-X^2,Y+X)\cong_\text{Ring} \mathbb{R}\times \mathbb{R}$
62566
Does $X\times S^1\cong Y\times S^1$ imply that $X\times\mathbb R\cong Y\times\mathbb R$?
109710
Bijection between $\mathbb N \times \mathbb N$ and $\mathbb N$
125814
The function $f(z)=z+\frac{1}{z}$ maps $\Omega$ biholomorphically on the upper plane
118192
Is there a bijective function $f: \mathbb{R}\to\mathbb{R}$ that is discontinuous?
80656
Is it possible to iterate a function transfinite times?
75970
$\mathbb Z[1/2]$ is not finitely generated?
91980
Prove that f is one-to-one on D
133636
Is $\mathbb Z[X]/(X^2-1)$ a domain?
35626
Is $(\mathbb{R}^2, lexicographic) \cong (\mathbb{R}, discrete)\times (\mathbb{R}, usual)$?
19355
prove $f(x)=x^3+x$ is one to one and onto
51334
Does there exist any surjective group homomorphism from $(\mathbb R^* , .)$ onto $(\mathbb Q^* , .)$?
86105
Can $\{(f(t),g(t)) \mid t\in [a,b]\}$ cover the entire square $[0,1] \times [0,1]$ ?
26749
$\mathbb{Z}[X]/(X^2-1)$ is not isomorphic with $\mathbb{Z}\times \mathbb{Z}$
68165
Find a function $f: \mathbb{R} \to \mathbb{R}$ that is continuous at precisely one point?