Explicit bijection between $\mathbb N$ and $\mathbb N \times \mathbb N$
54761
Inverting the Cantor pairing function
64130
Prove that $\mathbb{Q}^{\times}$ not isomorphic to $\mathbb{Z}^{n}$
130381
bijection from $(a,b)$ to $\Bbb R$
97878
Are there uncountably many surjections from $\mathbb N$ to $\mathbb N$?
49953
Proving that a function from $N\times N$ to $N$ is bijective.
124847
Is the set of surjective functions from $\mathbb{N}$ to $\mathbb{N}$ uncountable?
128652
Subgroups of $\mathbb Z \times(\mathbb Z/n\mathbb Z)$
93964
Proving that $f$ is a bijection from $N$x$N$ to $N$.
13761
Automorphisms in $\mathbb{Z}_n$
92211
When are $\mathbb Z_m$ and $\mathbb Z_n$ homomorphic?
64140
Find a bijection from $\mathbb R$ to $\mathbb R-\mathbb N$
133699
Proving that there is a bijection between $A$ and $B$.
78847
Bijection between Prime numbers and Natural numbers
119549
Prove the even integers are countable (by explicitly giving a bijection $\mathbb{N} \to E$)
50649
On the existence of a continuous bijection $f\colon [0,1]\to [0,1]\times [0,1]$
106884
Is there a continuous bijection between an interval $[0,1]$ and a square: $[0,1] \times [0,1]$?
70861
$\mathbb P^n\times \mathbb P^m\not\cong \mathbb P^{m+n}$