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[Merged by Bors] - feat(LinearAlgebra/QuadraticForm/Basic): more lemmas#7196

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[Merged by Bors] - feat(LinearAlgebra/QuadraticForm/Basic): more lemmas#7196
eric-wieser wants to merge 4 commits intomasterfrom
eric-wieser/more-QuadraticForm-lemmas

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This also adds a handful of missing lemmas about Set.center for inverses and numeric literals.


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@eric-wieser eric-wieser added awaiting-review 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 Sep 15, 2023
@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 Sep 15, 2023
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Thanks!

bors d+

rfl
#align quadratic_form.associated_apply QuadraticForm.associated_apply

theorem two_nsmul_associated : 2 • associatedHom S Q = Q.polarBilin := by
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theorem two_nsmul_associated : 2 • associatedHom S Q = Q.polarBilin := by
@[simp] theorem two_nsmul_associated : 2 • associatedHom S Q = Q.polarBilin := by

polarBilin (Q.baseChange A) = (polarBilin Q).baseChange A := by
rw [QuadraticForm.baseChange, BilinForm.baseChange, polarBilin_tmul, BilinForm.tmul,
←LinearMap.map_smul, smul_tmul', ←two_nsmul_associated R]
erw [associated_sq]
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How about adding something like:

lemma associatedHom_apply {R M S : Type*} [CommRing R]
    [AddCommGroup M] [Module R M] [CommRing S] [Algebra S R] [Invertible (2 : R)]
    (Q : QuadraticForm R M) :
    associatedHom S Q = associated Q := by
  rfl

just below the definition of associated and using it to avoid the erw (so that this whole proof just becomes one giant chain of rws).

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This associatedHom thing is a mess that I was considering cleaning up another time. I think the canonical spelling should be an unbundled one, with the hom available if needed.

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bors bot commented Sep 16, 2023

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

@ghost ghost added delegated This pull request has been delegated to the PR author (or occasionally another non-maintainer). and removed awaiting-review labels Sep 16, 2023
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bors merge

@github-actions github-actions bot added the ready-to-merge This PR has been sent to bors. label Sep 16, 2023
bors bot pushed a commit that referenced this pull request Sep 16, 2023
This also adds a handful of missing lemmas about `Set.center` for inverses and numeric literals.
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bors bot commented Sep 16, 2023

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@bors bors bot changed the title feat(LinearAlgebra/QuadraticForm/Basic): more lemmas [Merged by Bors] - feat(LinearAlgebra/QuadraticForm/Basic): more lemmas Sep 16, 2023
@bors bors bot closed this Sep 16, 2023
@bors bors bot deleted the eric-wieser/more-QuadraticForm-lemmas branch September 16, 2023 15:46
kodyvajjha pushed a commit that referenced this pull request Sep 22, 2023
This also adds a handful of missing lemmas about `Set.center` for inverses and numeric literals.
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