[Merged by Bors] - feat(SetTheory/Cardinal): helpers for Konig's theorem on bipartite graphs

[ksenono]

Implement helper lemmas for Konig's theorem on bipartite graphs

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[github-actions]

PR summary 11b0237d9d

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ add_lt_add
+ add_lt_add_iff_of_left_lt_aleph0
+ add_lt_add_iff_of_right_lt_aleph0
+ card_lt_card_of_left_finite
+ card_lt_card_of_right_finite
+ mul_natCast_inj
+ mul_natCast_le_mul_natCast
+ mul_natCast_lt_mul_natCast
+ mul_natCast_strictMono
+ natCast_mul_inj
+ natCast_mul_le_natCast_mul
+ natCast_mul_lt_natCast_mul
+ natCast_mul_strictMono

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).

[vihdzp]

Otherwise this LGTM. Please do tag me when you PR König's theorem itself!

[b-mehta]

Note Konig's theorem is in mathlib already: https://leanprover-community.github.io/mathlib4_docs/Mathlib/SetTheory/Cardinal/Order.html#Cardinal.sum_lt_prod. And Konig's lemma is also in mathlib: https://leanprover-community.github.io/mathlib4_docs/Mathlib/Order/KonigLemma.html#:~:text=K%C5%91nig's%20infinity%20lemma%20is%20most,has%20a%20number%20of%20formulations.
Perhaps you mean a different one, though?

[SnirBroshi]

Perhaps you mean a different one, though?

They're referring to the graph theory one #32531 Wikipedia

Interestingly, the set theory one was proved by a different König than the graph theory theorem and lemma- by his father.

[ksenono]

-awaiting-author

[j-loreaux]

bors d+

[mathlib-bors]

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

[vihdzp]

I think we should probably change the PR title as well, given that we have König's theorem already.

[ksenono]

bors r+

[mathlib-bors]

👎 Rejected by label

[SnirBroshi]

@ksenono I think the solution is to remove the "depends on" from the PR description, then wait a minute for the bot to remove the label "blocked-by-other-PR", then try again

[YaelDillies]

maintainer merge

[github-actions]

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

[b-mehta]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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