feat(AlgebraicTopology/SimplicialSet): the fundamental groupoid of horns

[joelriou]

---

• depends on: feat(AlgebraicTopology/SimplicialSet): the fundamental groupoid #42523
• depends on: feat(AlgebraicTopology/Simplex): edges of a subcomplex #42571

[github-actions]

PR summary 165f486ac3

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.AlgebraicTopology.SimplicialSet.FundamentalGroupoid.Basic (new file)	1028
Mathlib.AlgebraicTopology.SimplicialSet.FundamentalGroupoid.Horn (new file)	1029

---

Declarations diff (regex)

+ hom_rec
+ horn.card_le_of_edge
+ horn.compStruct
+ horn.edge'
+ horn.subsingleton_edge
+ instance {X Y : SSet.Truncated.{u} 2} (f : X ⟶ Y) [IsIso f] :
+ instance {n : ℕ} (i : Fin (n + 1)) [NeZero n] :
+ instance {n : ℕ} (x y : (Δ[n] : SSet.{u}) _⦋0⦌) : Subsingleton (Edge x y)
+ isEquivalence_mapFundamentalGroupoid
+ isEquivalence_of_isEquivalence_toPUnit
+ isEquivalence_toPUnit_horn
+ isEquivalence_toPUnit_stdSimplex
+ isoCatMapFundamentalGroupoid
+ mapFundamentalGroupoid_comp
+ mapFundamentalGroupoid_id
+ mapHomotopyCategory_comp
+ mapHomotopyCategory_id
+ mapIsoFundamentalGroupoid
+ mk_surjective
+ rec
+ stdSimplex.compStruct
+ stdSimplex.edge'
+ stdSimplex.edge_one
+ stdSimplex.edge_zero
+ toPUnit
++ FundamentalGroupoid
++ homMk
++ homMk_comp
++ homMk_id
++ isEquivalence_toPUnit
++ mapFundamentalGroupoid
++ mk

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

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

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

Declarations diff (Lean -- pending)

Computed after the build finishes.

---

Increase in strong tech debt: (relative, absolute) = (1.00, 1.00)

Current number	Change	Type (strong)
1	1	maxHeartBeats modifications
6987	1	backward.isDefEq.respectTransparency

Increase in weak tech debt: (relative, absolute) = (2.00, 0.00)

Current number	Change	Type (weak)
5049	2	exposed public sections

Current commit 165f486ac3
Reference commit 9fb10993c1

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/scripts/reporting/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).

[mathlib-dependent-issues]

This PR/issue depends on:

• feat(AlgebraicTopology/SimplicialSet): the fundamental groupoid #42523
• feat(AlgebraicTopology/Simplex): edges of a subcomplex #42571
  By Dependent Issues (🤖). Happy coding!