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[Merged by Bors] - feat(category_theory/limits): products give pullback squares #14327

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Follow-up to #14220


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@semorrison semorrison requested a review from erdOne May 23, 2022 08:08
@semorrison semorrison added awaiting-review The author would like community review of the PR awaiting-CI The author would like to see what CI has to say before doing more work. labels May 23, 2022
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I'll do biproducts giving bicartesian squares shortly.

Comment on lines 119 to +122
def is_pushout_of_is_initial_is_coproduct {W X Y Z : C} (f : X ⟶ Z) (g : Y ⟶ Z) (h : W ⟶ X)
(k : W ⟶ Y) (H₁ : is_terminal Z)
(H₂ : is_limit (binary_fan.mk h k)) :
is_limit (pullback_cone.mk _ _ (show h ≫ f = k ≫ g, from H₁.hom_ext _ _)) :=
(k : W ⟶ Y) (H₁ : is_initial W)
(H₂ : is_colimit (binary_cofan.mk f g)) :
is_colimit (pushout_cocone.mk _ _ (show h ≫ f = k ≫ g, from H₁.hom_ext _ _)) :=
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Apparently this had been copy-pasted ready for dualisation in #10581, but then only the declaration name was dualised!

@github-actions github-actions bot removed the awaiting-CI The author would like to see what CI has to say before doing more work. label May 23, 2022
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Thanks 🎉

bors merge

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bors bot commented May 25, 2022

Merge conflict.

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bors merge

@github-actions github-actions bot added ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) and removed awaiting-review The author would like community review of the PR labels May 25, 2022
bors bot pushed a commit that referenced this pull request May 25, 2022
Follow-up to #14220



Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
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bors bot commented May 25, 2022

Build failed:

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bors merge

bors bot pushed a commit that referenced this pull request May 26, 2022
Follow-up to #14220



Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
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bors bot commented May 26, 2022

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(category_theory/limits): products give pullback squares [Merged by Bors] - feat(category_theory/limits): products give pullback squares May 26, 2022
@bors bors bot closed this May 26, 2022
@bors bors bot deleted the semorrison/pullback_square2 branch May 26, 2022 06:41
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