How to prove a function from $\mathbb N\times \mathbb N$ to $\mathbb N$ is bijective.
49953
Proving that a function from $N\times N$ to $N$ is bijective.
139833
Prove that $\gcd(M, N)\times \mbox{lcm}(M, N) = M \times N$.
110569
Does anyone know a closed-form expression for a bijection between $\mathbb{N}^k$ and $\mathbb{N}$?
140440
Proving $(A\times C)\cup(B\times D)\subseteq(A\cup B)\times(C\cup D)$
27188
Bijection between $\mathbb{R}$ and $\mathbb{R}/\mathbb{Q}$
39231
Construct a bijection between $\mathbb{Z}^+\times \mathbb{Z}^+$ and $\mathbb{Z}^+$
6161
The cartesian product $\mathbb{N} \times \mathbb{N}$ is countable
14277
Proving $f(x)=x\cdot |x|$ is a bijection
26169
Function $f: \mathbb{R} \to \mathbb{R}$ that takes each value in $\mathbb{R}$ three times
13253
Prove $f(S \cup T) = f(S) \cup f(T)$
21391
Proving Functions are Surjective
67451
Building a bijection from a finite union of countable sets to $\mathbb{N}$
16092
How to prove that the composition of two surjective functions is surjective
24561
$\mathbb S_n$ as semidirect product
55393
Existence of a group isomorphism between $(\mathbb K,+)$ and $(\mathbb K^\times,\cdot)$
45991
Why $f\colon \mathbb{Z}_n^\times \to \mathbb{Z}_m^\times$ is surjective?
83001
Easier way to show $(\mathbb{Z}/(n))[x]$ and $\mathbb{Z}[x] / (n)$ are isomorphic