Right/Left-exactness in Abelian categories
51786
Is every additive monofunctor between abelian categories left exact?
127826
Is the geometric realization of a pointed category contractible?
81423
Completeness and Topological Equivalence
17997
Right identity and Right inverse implies a group
79591
Exact Sequences of Modules and Rank
154142
Finding a specific basis for an endomorphism
86823
proof verification: If $f:G \rightarrow H$ is group homomorphism, and $H$ is abelian, then $G$ is abelian
93040
$f$ is surjective iff it has a right inverse: using the axiom of choice and errors in ProofWiki
74617
Equivalent conditions for a preabelian category to be abelian
34300
"Natural" categories where monomorphisms differ from injective morphisms
141900
Exact sequence and Noetherian modules
6904
questions about extremal epimorphisms in category theory
15320
Morita equivalence and right and left ideals of a Ring
35140
Existence of minimal $\sigma$-algebra and transfinite induction
117479
Mutual set of representatives for left and right cosets: what about infinite groups?
110110
Mitchell's Embedding Theorem for not-necessarily-small categories
124003
Composition of adjoint functors