feat(Algebra/Homology): functoriality of ProjectiveResolution.extMk

[joelriou]

Given a fixed projective (resp. injective) resolution R, we obtain the functoriality of the constructor R.extMk.

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• depends on: feat(CategoryTheory): computing Ext-groups using a projective resolution #32816

[github-actions]

PR summary 8d7d30cfc0

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.CategoryTheory.Abelian.Projective.Ext (new file)	1292

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Declarations diff

+ Cocycle.postcomp
+ Cocycle.precomp
+ add_extMk
+ equivHomShift_comp
+ equivHomShift_comp_shift
+ equivHomShift_symm_postcomp
+ equivHomShift_symm_precomp
+ extAddEquivCohomologyClass
+ extEquivCohomologyClass
+ extEquivCohomologyClass_add
+ extEquivCohomologyClass_extMk
+ extEquivCohomologyClass_neg
+ extEquivCohomologyClass_sub
+ extEquivCohomologyClass_symm_add
+ extEquivCohomologyClass_symm_mk_hom
+ extEquivCohomologyClass_symm_neg
+ extEquivCohomologyClass_symm_sub
+ extEquivCohomologyClass_symm_zero
+ extEquivCohomologyClass_zero
+ extMk
+ extMk_comp_mk₀
+ extMk_eq_zero_iff
+ extMk_surjective
+ extMk_zero
+ fromSingleEquiv_fromSingleMk
+ instance : R.cochainComplex.IsKProjective := isKProjective_of_projective _ 0
+ mk₀_comp_extMk
+ neg_extMk
+ sub_extMk
+ toSingleEquiv_toSingleMk
++ fromSingleMk_precomp
++ toSingleMk_postcomp

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[mathlib4-dependent-issues-bot]

This PR/issue depends on:

• feat(CategoryTheory): computing Ext-groups using a projective resolution #32816
  By Dependent Issues (🤖). Happy coding!