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[Merged by Bors] - feat(category_theory): preadditive binary biproducts #2747
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Originally, I for some reason believed that in a preadditve category, every binary biproduct is automatically a preadditive binary biproduct. This is of course not true, which makes this PR a bit less nice than I had originally hoped, but I hope it's fine. This PR introduces two |
Also, move everything over to biproducts.lean
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LGTM
Thanks 🎉 bors merge |
This PR introduces "preadditive binary biproducts", which correspond to the second definition of biproducts given in #2177. * Preadditive binary biproducts are binary biproducts. * In a preadditive category, a binary product is a preadditive binary biproduct. * This directly implies that `AddCommGroup` has preadditive binary biproducts. The existence of binary coproducts in `AddCommGroup` is then a consequence of abstract nonsense.
Pull request successfully merged into master. Build succeeded: |
…unity#2747) This PR introduces "preadditive binary biproducts", which correspond to the second definition of biproducts given in leanprover-community#2177. * Preadditive binary biproducts are binary biproducts. * In a preadditive category, a binary product is a preadditive binary biproduct. * This directly implies that `AddCommGroup` has preadditive binary biproducts. The existence of binary coproducts in `AddCommGroup` is then a consequence of abstract nonsense.
This PR introduces "preadditive binary biproducts", which correspond to the second definition of biproducts given in #2177.
AddCommGroup
has preadditive binary biproducts. The existence of binary coproducts inAddCommGroup
is then a consequence of abstract nonsense.