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[Merged by Bors] - feat(CategoryTheory): naturality of the connecting homomorphism of the snake lemma #8490

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@joelriou joelriou commented Nov 18, 2023

In this PR, it is shown that the connecting homomorphism of the snake lemma is natural.


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@leanprover-community-mathlib4-bot leanprover-community-mathlib4-bot added the blocked-by-other-PR This PR depends on another PR to Mathlib (this label is automatically managed by a bot) label Nov 18, 2023
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Thanks 🎉

bors merge

Comment on lines +32 to +36
`L₀.X₁ ⟶ L₀.X₂ ⟶ L₀.X₃ ⟶ L₃.X₁ ⟶ L₃.X₂ ⟶ L₃.X₃`. Each of the four exactness
statement is first stated separately as lemmas `L₀_exact`, `L₁'_exact`,
`L₂'_exact` and `L₃_exact` and the full 6-term exact sequence is stated
as `snake_lemma`. This sequence can even be extended with an extra `0`
on the left (see `mono_L₀_f`) if `L₁.X₁ ⟶ L₁.X₂` is a mono (i.e. `L₁` is short exact),
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`L₀.X₁ ⟶ L₀.X₂ ⟶ L₀.X₃ ⟶ L₃.X₁ ⟶ L₃.X₂ ⟶ L₃.X₃`. Each of the four exactness
statement is first stated separately as lemmas `L₀_exact`, `L₁'_exact`,
`L₂'_exact` and `L₃_exact` and the full 6-term exact sequence is stated
as `snake_lemma`. This sequence can even be extended with an extra `0`
on the left (see `mono_L₀_f`) if `L₁.X₁ ⟶ L₁.X₂` is a mono (i.e. `L₁` is short exact),
`L₀.X₁ ⟶ L₀.X₂ ⟶ L₀.X₃ ⟶ L₃.X₁ ⟶ L₃.X₂ ⟶ L₃.X₃`. Each of the four exactness
statements is first stated separately as lemma `L₀_exact`, `L₁'_exact`,
`L₂'_exact` and `L₃_exact` and the full 6-term exact sequence is stated
as `snake_lemma`. This sequence can even be extended with an extra `0`
on the left (see `mono_L₀_f`) if `L₁.X₁ ⟶ L₁.X₂` is a mono (i.e. `L₁` is short exact),

@leanprover-community-mathlib4-bot leanprover-community-mathlib4-bot added ready-to-merge This PR has been sent to bors. and removed awaiting-review labels Nov 28, 2023
mathlib-bors bot pushed a commit that referenced this pull request Nov 28, 2023
…e snake lemma (#8490)

In this PR, it is shown that the connecting homomorphism of the snake lemma is natural.
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mathlib-bors bot commented Nov 28, 2023

Pull request successfully merged into master.

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@mathlib-bors mathlib-bors bot changed the title feat(CategoryTheory): naturality of the connecting homomorphism of the snake lemma [Merged by Bors] - feat(CategoryTheory): naturality of the connecting homomorphism of the snake lemma Nov 28, 2023
@mathlib-bors mathlib-bors bot closed this Nov 28, 2023
@mathlib-bors mathlib-bors bot deleted the snake-naturality branch November 28, 2023 15:31
awueth pushed a commit that referenced this pull request Dec 19, 2023
…e snake lemma (#8490)

In this PR, it is shown that the connecting homomorphism of the snake lemma is natural.
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3 participants