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[Merged by Bors] - feat(RingTheory/LinearDisjoint): properties of linearly disjoint of subalgebras (2)#15346

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[Merged by Bors] - feat(RingTheory/LinearDisjoint): properties of linearly disjoint of subalgebras (2)#15346
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@acmepjz acmepjz commented Jul 30, 2024

Some new results:

  • Subalgebra.LinearDisjoint.rank_sup_of_free,
    Subalgebra.LinearDisjoint.finrank_sup_of_free:
    if subalgebras A and B are linearly disjoint and they are
    free modules, then the rank of A ⊔ B is equal to the product of the rank of A and B.

  • Subalgebra.LinearDisjoint.of_finrank_sup_of_free:
    conversely, if A and B are subalgebras which are free modules of finite rank,
    such that rank of A ⊔ B is equal to the product of the rank of A and B,
    then A and B are linearly disjoint.

  • Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_left:
    Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_right:
    if A and B are linearly disjoint, if A is free and B is flat (resp. B is free and
    A is flat), then [B[A] : B] = [A : R] (resp. [A[B] : A] = [B : R]).
    See also Subalgebra.adjoin_rank_le.

  • Subalgebra.LinearDisjoint.of_finrank_coprime_of_free:
    if the rank of A and B are coprime, and they satisfy some freeness condition,
    then A and B are linearly disjoint.


discussion: https://leanprover.zulipchat.com/#narrow/stream/217875-Is-there-code-for-X.3F/topic/Linearly.20disjoint

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@acmepjz acmepjz added awaiting-CI This PR does not pass CI yet. This label is automatically removed once it does. t-algebra Algebra (groups, rings, fields, etc) labels Jul 30, 2024
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github-actions bot commented Jul 30, 2024

PR summary aaa7fe6e3c

Import changes for modified files

Dependency changes

File Base Count Head Count Change
Mathlib.RingTheory.LinearDisjoint 1585 1586 +1 (+0.06%)
Import changes for all files
Files Import difference
Mathlib.RingTheory.LinearDisjoint 1

Declarations diff

+ adjoin_rank_eq_rank_left
+ adjoin_rank_eq_rank_right
+ finrank_sup_of_free
+ of_finrank_coprime_of_free
+ of_finrank_sup_of_free
+ rank_eq_one_of_commute_of_flat_of_self_of_inj
+ rank_eq_one_of_flat_of_self_of_inj
+ rank_inf_eq_one_of_commute_of_flat_left_of_inj
+ rank_inf_eq_one_of_commute_of_flat_of_inj
+ rank_inf_eq_one_of_commute_of_flat_right_of_inj
+ rank_inf_eq_one_of_flat_left_of_inj
+ rank_inf_eq_one_of_flat_of_inj
+ rank_inf_eq_one_of_flat_right_of_inj
+ rank_sup_of_free

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.

@github-actions github-actions bot removed the awaiting-CI This PR does not pass CI yet. This label is automatically removed once it does. label Jul 30, 2024
@ghost ghost added the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Jul 31, 2024
@ghost ghost removed the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Aug 22, 2024
@acmepjz acmepjz added the awaiting-author A reviewer has asked the author a question or requested changes. label Aug 22, 2024
@acmepjz acmepjz removed the awaiting-author A reviewer has asked the author a question or requested changes. label Sep 3, 2024
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This PR is very long. Are you sure that you want a one field structure for your definition of LinearDisjoint?

@acmepjz acmepjz added the awaiting-author A reviewer has asked the author a question or requested changes. label Oct 16, 2024
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acmepjz commented Oct 16, 2024

This PR is very long.

Fine. I'll try to split this as two separate PRs. Note that the first one can only contain very basic results which can almost do nothing.

@acmepjz acmepjz changed the title feat(RingTheory/LinearDisjoint): definition and properties of linearly disjoint of subalgebras feat(RingTheory/LinearDisjoint): definition and properties of linearly disjoint of subalgebras (2) Oct 16, 2024
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acmepjz commented Oct 16, 2024

OK I've split half of them to #17820. It's 450 lines but I think it can't be shorten. Please review it first.

@acmepjz acmepjz added blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) and removed awaiting-author A reviewer has asked the author a question or requested changes. labels Oct 16, 2024
@mathlib4-dependent-issues-bot mathlib4-dependent-issues-bot removed the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Oct 28, 2024
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# Conflicts:
#	Mathlib/RingTheory/LinearDisjoint.lean
@acmepjz acmepjz changed the title feat(RingTheory/LinearDisjoint): definition and properties of linearly disjoint of subalgebras (2) feat(RingTheory/LinearDisjoint): properties of linearly disjoint of subalgebras (2) Oct 28, 2024
@acmepjz acmepjz removed the merge-conflict The PR has a merge conflict with master, and needs manual merging. (this label is managed by a bot) label Oct 28, 2024
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erdOne commented Oct 29, 2024

Thanks!
maintainer merge

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

@github-actions github-actions bot added the maintainer-merge A reviewer has approved the changed; awaiting maintainer approval. label Oct 29, 2024
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Thanks!

bors merge

@github-actions github-actions bot added the ready-to-merge This PR has been sent to bors. label Oct 29, 2024
mathlib-bors bot pushed a commit that referenced this pull request Oct 29, 2024
…ubalgebras (2) (#15346)

Some new results:

- `Subalgebra.LinearDisjoint.rank_sup_of_free`,
  `Subalgebra.LinearDisjoint.finrank_sup_of_free`:
  if subalgebras `A` and `B` are linearly disjoint and they are
  free modules, then the rank of `A ⊔ B` is equal to the product of the rank of `A` and `B`.

- `Subalgebra.LinearDisjoint.of_finrank_sup_of_free`:
  conversely, if `A` and `B` are subalgebras which are free modules of finite rank,
  such that rank of `A ⊔ B` is equal to the product of the rank of `A` and `B`,
  then `A` and `B` are linearly disjoint.

- `Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_left`:
  `Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_right`:
  if `A` and `B` are linearly disjoint, if `A` is free and `B` is flat (resp. `B` is free and
  `A` is flat), then `[B[A] : B] = [A : R]` (resp. `[A[B] : A] = [B : R]`).
  See also `Subalgebra.adjoin_rank_le`.

- `Subalgebra.LinearDisjoint.of_finrank_coprime_of_free`:
  if the rank of `A` and `B` are coprime, and they satisfy some freeness condition,
  then `A` and `B` are linearly disjoint.
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mathlib-bors bot commented Oct 29, 2024

Pull request successfully merged into master.

Build succeeded:

@mathlib-bors mathlib-bors bot changed the title feat(RingTheory/LinearDisjoint): properties of linearly disjoint of subalgebras (2) [Merged by Bors] - feat(RingTheory/LinearDisjoint): properties of linearly disjoint of subalgebras (2) Oct 29, 2024
@mathlib-bors mathlib-bors bot closed this Oct 29, 2024
@mathlib-bors mathlib-bors bot deleted the acmepjz_lin_disj_subalg branch October 29, 2024 12:26
jcommelin pushed a commit that referenced this pull request Oct 29, 2024
…ubalgebras (2) (#15346)

Some new results:

- `Subalgebra.LinearDisjoint.rank_sup_of_free`,
  `Subalgebra.LinearDisjoint.finrank_sup_of_free`:
  if subalgebras `A` and `B` are linearly disjoint and they are
  free modules, then the rank of `A ⊔ B` is equal to the product of the rank of `A` and `B`.

- `Subalgebra.LinearDisjoint.of_finrank_sup_of_free`:
  conversely, if `A` and `B` are subalgebras which are free modules of finite rank,
  such that rank of `A ⊔ B` is equal to the product of the rank of `A` and `B`,
  then `A` and `B` are linearly disjoint.

- `Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_left`:
  `Subalgebra.LinearDisjoint.adjoin_rank_eq_rank_right`:
  if `A` and `B` are linearly disjoint, if `A` is free and `B` is flat (resp. `B` is free and
  `A` is flat), then `[B[A] : B] = [A : R]` (resp. `[A[B] : A] = [B : R]`).
  See also `Subalgebra.adjoin_rank_le`.

- `Subalgebra.LinearDisjoint.of_finrank_coprime_of_free`:
  if the rank of `A` and `B` are coprime, and they satisfy some freeness condition,
  then `A` and `B` are linearly disjoint.
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