[Merged by Bors] - feat(CategoryTheory/Sites): pullback point along flat functor

[chrisflav]

For F : C ⥤ D a representably flat and cover preserving functor between sites, we construct
a point on C from a point on D by precomposing the fiber functor with F.

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[github-actions]

PR summary d1366e1a1a

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.CategoryTheory.Sites.Point.Basic	1119	1129	+10 (+0.89%)

Import changes for all files

Files	Import difference
Mathlib.CategoryTheory.Sites.Point.Basic Mathlib.CategoryTheory.Sites.Point.Category	10

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Declarations diff

+ comap
+ instance (G : D ⥤ Type*) [RepresentablyFlat F] [IsCofiltered G.Elements] :
+ instance (X : E) [RepresentablyCoflat F] : (CostructuredArrow.pre F G X).Initial
+ instance (X : E) [RepresentablyCoflat F] [h : IsFiltered (CostructuredArrow G X)] :
+ instance (X : E) [RepresentablyFlat F] : (StructuredArrow.pre X F G).Final
+ instance (X : E) [RepresentablyFlat F] [IsCofiltered (StructuredArrow X G)] :
+ isCofiltered_op_iff_isFiltered
+ isFiltered_op_iff_isCofiltered
++ iff_of_equivalence

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).

[joelriou]

Thanks!

bors d+

[mathlib-bors]

✌️ chrisflav can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[chrisflav]

Thanks!
bors r+

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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