List questions from diagram-chasing | MathQA

Short exact sequence of modules induces short exact sequence of cokernels

Published on 19 Jul 2022 - 15:58

Why does this diagram commute by uniqueness of the maps?

Published on 27 Jul 2022 - 21:22

What on Earth does Lang mean by "write the second square in the form..." in proof of Lemma 5.2, Homotopies of Morphiphsms of Complexes?

Published on 30 Jul 2022 - 14:50

Question on the exactness at the third kernel $\ker\nu$ in the Snake Lemma

Published on 02 Aug 2022 - 5:32

Does the Barr-embedding preserve coequalizers

Published on 13 Aug 2022 - 22:21

How do you express that two commutative diagrams can be glued together along a common subgraph and retain commutativity?

Published on 13 Sep 2022 - 4:27

Difficulty proving the second isomorphism theorem: $\frac{X}{X\cap Y}\cong\frac{X\cup Y}{Y}$ in an Abelian category

Published on 23 Mar 2026 - 3:40

How to show excisive triad symmetric from the Eilenberg-Steenrod axioms

Published on 30 Oct 2022 - 13:54

Exact sequence induced by filtration

Published on 04 Dec 2022 - 18:55

Lifting property for Hausdorff spaces

Published on 27 Jan 2023 - 18:56