Existence of injection or surjection between two given sets
39708
Proving $(A\le B)\vee (B\le A)$ for sets $A$ and $B$
152613
Injection from $\mathbb{N}\to\{0,1\}$ to the set of all monotonic decreasing functions from $\mathbb{N}\to\mathbb{Z}$
84114
Does there exist a surjective homomorphism from $(\mathbb R,+)$ to $(\mathbb Q,+)$ ?
133699
Proving that there is a bijection between $A$ and $B$.
140668
Union of $2$ set $A, B$ where $ A$ is a subset of $B$
88982
Prove that for any two sets $A$ and $B$, $A\notin B$ or $B\notin A$
44689
Explicit bijection between $[0,1)$ and $(0,1)$
21707
Constructing a Bijective function via an injective and surjective one.
19414
Uncountable subset with uncountable complement, without the Axiom of Choice
24045
Efficiently compute Intersection of two Sets in Java?
18334
Equivalence between CH and existence of certain sets in $\mathbb{R}^2$
20303
A function $f\colon E\to F$ between finite sets is injective iff it is surjective iff it is bijective
21663
Bijection between power sets of sets implies bijection between sets?
130363
Prove composition of two surjections is surjection
74453
Injective and Surjective Functions
132692
Nonempty set mapped to $\emptyset$ and vice-versa
73526
The equivalence of "Every surjection has a right inverse" and the Axiom of Choice