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[Merged by Bors] - feat(category_theory/idempotents): biproducts in idempotent completions #12333

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@joelriou joelriou commented Feb 27, 2022


If C is an additive category, then karoubi C is an additive category.

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@joelriou joelriou changed the title feat (category_theory/idempotents): biproducts in idempotent completions feat(category_theory/idempotents): biproducts in idempotent completions Feb 27, 2022
@joelriou joelriou marked this pull request as draft February 27, 2022 11:21
@joelriou joelriou marked this pull request as ready for review February 28, 2022 08:50
@joelriou joelriou added the awaiting-review The author would like community review of the PR label Feb 28, 2022
{ X :=
{ X := biproduct (λ j, (F j).X),
p := biproduct.map (λ j, (F j).p),
idempotence := begin
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Maybe this ship has sailed, but idempotent would have been a better name than idempotence here: it's too hard in English to consistently come up with variants of words that mean "the property of being X", and it's easier to consistently just say "X".

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What about the shorter idem? (Similarly as factori[sz]ation is often shortened as fac in other places in mathlib.) May I do such a change slightly later in a separate PR?

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Sure, either idempotent or idem are good as far as I'm concerned. Yes -- no need to worry about it for this PR, but it would be nice if we eventually get to it.

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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 Mar 1, 2022
bors bot pushed a commit that referenced this pull request Mar 1, 2022
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bors bot commented Mar 1, 2022

Pull request successfully merged into master.

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@bors bors bot changed the title feat(category_theory/idempotents): biproducts in idempotent completions [Merged by Bors] - feat(category_theory/idempotents): biproducts in idempotent completions Mar 1, 2022
@bors bors bot closed this Mar 1, 2022
@bors bors bot deleted the karoubi_biproducts branch March 1, 2022 03:24
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