Surjection Equivalence
93102
prove that $f:X\rightarrow Y$ is surjective if and only if $f(f^{-1}(C))=C$
45380
Surjectivity implies injectivity and conversely
45991
Why $f\colon \mathbb{Z}_n^\times \to \mathbb{Z}_m^\times$ is surjective?
28798
Proving injection and surjection with functions $F:C^B\to C^A$, $F(f)=f\circ\varphi$, $\varphi: A\to B$
10679
Equivalence of Categories and of Their Functor Categories
40566
Counting surjective functions
84114
Does there exist a surjective homomorphism from $(\mathbb R,+)$ to $(\mathbb Q,+)$ ?
136883
The class of equivalence.
40415
Why do we require quotient to be surjective?
106830
are $f(f(x))=f(x)$ and $f(x)=x$ equivalent?
21707
Constructing a Bijective function via an injective and surjective one.
158892
Surjective endomorphism of abelian group is isomorphism
44689
Explicit bijection between $[0,1)$ and $(0,1)$
5635
How to prove that the Frobenius endomorphism is surjective?
46748
If $g \circ f$ is surjective, show that $f$ does not have to be surjective?
53168
Surjective, Injective, Bijective Functions from $\mathbb Z$ to itself
70912
If $g\circ f$ is injective and $f$ is surjective then $g$ is injective