[Merged by Bors] - feat(Data/Multiset/Order): add Dershowitz-Manna Ordering and Theorem

[haitian-yuki]

add Dershowitz-Manna Ordering and Theorem for Multisets

Co-authored-by: Malvin Gattinger [email protected]

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• depends on: [Merged by Bors] - feat: Multiset lemmas #15645

https://leanprover.zulipchat.com/#narrow/stream/113489-new-members/topic/Dershowitz-Manna.20Ordering.20theorem/near/434390710

[github-actions]

PR summary 85739c0726

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.Data.Multiset.DershowitzManna (new file)	393

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Declarations diff

+ IsDershowitzMannaLT
+ IsDershowitzMannaLT.trans
+ instWellFoundedisDershowitzMannaLT
+ wellFounded_isDershowitzMannaLT
++ add_add_tsub_cancel

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).

[riccardobrasca]

Can you please mark this PR WIP or awaiting-review? Thanks!

[Rida-Hamadani]

Thank you! Some comments are general and need to be applied in other places in PR (instead of just committing the suggested portions).

[kim-em]

Obviously my review is far from complete, but I'm not an expert here so hopefully someone else will come along, but these will give you something to start with.

[mathlib4-dependent-issues-bot]

This PR/issue depends on:

• [Merged by Bors] - feat: Multiset lemmas #15645
  By Dependent Issues (🤖). Happy coding!

[haitian-yuki]

Thanks again for another golf @YaelDillies ! I have to say it looks pretty clean to me now and I cannot see much to improve here ;-) Does it mean the PR is done now? Thanks!

[YaelDillies]

I'm hoping to do a third golf pass at some point next week (I am completely submerged right now), then yes it should be good 😄

[YaelDillies]

Sorry for the delay, but here's the final golf. Thank you for your patience!

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by YaelDillies.

[kim-em]

There's still an unresolved review comment above.

[kim-em]

bors merge

[mathlib-bors]

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[mathlib-bors]

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[mathlib-bors]

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[bryangingechen]

bors r+
bors d+

[mathlib-bors]

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

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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