feat(Data/Finsupp): support of mapDomain is image of support if nonneg

[YaelDillies]

Moves

• Finsupp.mapDomain_apply -> Finsupp.mapDomain_apply_of_injective

to make space for the more general lemma that doesn't assume injectivity.

---

[github-actions]

PR summary fbf13c9d57

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.Algebra.Order.BigOperators.Group.Finset	681	682	+1 (+0.15%)
Mathlib.Data.Finsupp.Order	854	855	+1 (+0.12%)

Import changes for all files

Files

Import difference

18 files Mathlib.Algebra.Order.BigOperators.Group.Finset Mathlib.Algebra.Order.Group.Int.Sum Mathlib.Algebra.Order.Ring.GeomSum Mathlib.Combinatorics.Additive.SubsetSum Mathlib.Combinatorics.Colex Mathlib.Combinatorics.Enumerative.Composition Mathlib.Combinatorics.Enumerative.Partition.Basic Mathlib.Combinatorics.SetFamily.KruskalKatona Mathlib.Data.Finsupp.Antidiagonal Mathlib.Data.Finsupp.Interval Mathlib.Data.Finsupp.Lex Mathlib.Data.Finsupp.MonomialOrder Mathlib.Data.Finsupp.Order Mathlib.Data.Finsupp.WellFounded Mathlib.Data.NNRat.BigOperators Mathlib.Data.Set.Equitable Mathlib.Geometry.Group.Growth.QuotientInter Mathlib.Logic.Hydra

1

---

Declarations diff (regex)

+ mapDomain_apply_of_injective
+ prod_comapDomain
+ support_mapDomain_of_nonneg
- sum_comapDomain

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.

---

No changes to strong technical debt.
No changes to weak technical debt.

Current commit fbf13c9d57
Reference commit d1298f10ae

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.py 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).

[eric-wieser]

nit: use the "moves" section of the PR template

bors d+

[mathlib-bors]

✌️ YaelDillies can now approve this pull request until 2026-09-23 09:49 UTC (in 2 weeks). To approve and merge, reply with bors r+. More detailed instructions are available here.

⚠️ This delegation only covers changes within Archive/**, Counterexamples/**, docs/**, DownstreamTest/**, Mathlib/**, MathlibTest/**, Wanted/**, widget/**, Archive.lean, Counterexamples.lean, docs.lean, Mathlib.lean, Wanted.lean; an author commit touching anything else will revoke it. Bors also revokes it if a later push changes too many files for it to check the full list — even if it stays within scope.