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[Merged by Bors] - feat: local inverse of a diffeomorphism#23219

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MR-local-diffeos-localInverse
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[Merged by Bors] - feat: local inverse of a diffeomorphism#23219
grunweg wants to merge 1 commit intomasterfrom
MR-local-diffeos-localInverse

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@grunweg grunweg commented Mar 22, 2025

Add IsLocalDiffeomorphAt.localInverse, a (choice of) local inverse for a local diffeomorphism at x. Prove basic API about it: if f is a local diffeomorphism at x, we prove that

  • f and its local inverse near x are local inverses (in both directions),
  • composing f and its local inverse is EventuallyEq to the identity near x.
  • smoothness results for the local inverse.

PR #8738 will use this to prove that the differential of a local diffeomorphism is a continuous linear equivalence.


I wondered if adding the analogous IsLocalDiffeomorph.localInverseAt would be useful: if so, I'll be happy to add it.

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Add IsLocalDiffeomorphAt.localInverse, a (choice of) local inverse
for a local diffeomorphism at x. Prove basic API about it: if f is a local
diffeomorphism at x, we prove that
- f and its local inverse near x are local inverses (in both directions),
- composing f and its local inverse is EventuallyEq to the identity near x.
- smoothness results for the local inverse.

PR #8738 will use this to prove that the differential of a local diffeomorphism
is a continuous linear equivalence.
@grunweg grunweg added the t-differential-geometry Manifolds etc label Mar 22, 2025
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PR summary d0e79dbd13

Import changes for modified files

No significant changes to the import graph

Import changes for all files
Files Import difference

Declarations diff

+ PartialDiffeomorph.isLocalDiffeomorphAt
+ contmdiffOn_localInverse
+ localInverse
+ localInverse_contMDiffAt
+ localInverse_contMDiffOn
+ localInverse_eqOn_left
+ localInverse_eqOn_right
+ localInverse_eventuallyEq_left
+ localInverse_eventuallyEq_right
+ localInverse_isLocalDiffeomorphAt
+ localInverse_left_inv
+ localInverse_mdifferentiableAt
+ localInverse_mem_source
+ localInverse_mem_target
+ localInverse_open_source
+ localInverse_right_inv

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.


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).

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Thanks 🎉

bors merge

@ghost ghost added the ready-to-merge This PR has been sent to bors. label Mar 25, 2025
mathlib-bors bot pushed a commit that referenced this pull request Mar 25, 2025
Add IsLocalDiffeomorphAt.localInverse, a (choice of) local inverse for a local diffeomorphism at x. Prove basic API about it: if f is a local diffeomorphism at x, we prove that
- f and its local inverse near x are local inverses (in both directions),
- composing f and its local inverse is EventuallyEq to the identity near x.
- smoothness results for the local inverse.

PR #8738 will use this to prove that the differential of a local diffeomorphism is a continuous linear equivalence.
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mathlib-bors bot commented Mar 25, 2025

Pull request successfully merged into master.

Build succeeded:

@mathlib-bors mathlib-bors bot changed the title feat: local inverse of a diffeomorphism [Merged by Bors] - feat: local inverse of a diffeomorphism Mar 25, 2025
@mathlib-bors mathlib-bors bot closed this Mar 25, 2025
@mathlib-bors mathlib-bors bot deleted the MR-local-diffeos-localInverse branch March 25, 2025 13:37
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