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[Merged by Bors] - feat(representation_theory/group_cohomology_resolution): show k[G^(n + 1)] is free over k[G] #15501
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I've not looked at the later parts of this PR but here are some comments on the earlier parts.
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This is looking really nice now. I've read through to the end. Well done for making the proofs so compact!
@[simp] lemma prod_unique_apply {α β : Type*} [unique β] (x : α × β) : | ||
prod_unique α β x = x.1 := rfl | ||
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@[simp] lemma prod_unique_symm_apply {α β : Type*} [unique β] (x : α) : |
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Similarly here:
@[simp] lemma prod_unique_symm_apply {α β : Type*} [unique β] (x : α) : | |
@[simp] lemma coe_prod_unique_symm {α β : Type*} [unique β] : | |
⇑(prod_unique α β).symm = pi.prod (id : α → α) default := rfl | |
lemma prod_unique_symm_apply {α β : Type*} [unique β] (x : α) : |
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It seems logic/equiv/basic
doesn't import data/pi/algebra
where pi.prod
is defined, and vice versa :(
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Is there some kind of tool which finds the first file which imports both logic/equiv/basic
and data/pi/algebra
?
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Thanks 🎉
bors merge
…+ 1)] is free over k[G] (#15501) Defines an isomorphism $k[G^{n + 1}] \cong k[G] \otimes_k k[G^n].$ Also shows that given a $k$-algebra $R$ and a $k$-basis for a module $M,$ we get an $R$-basis of $R \otimes_k M.$ Then, using that, we show $k[G^{n + 1}]$ is free.
Pull request successfully merged into master. Build succeeded: |
Defines an isomorphism$k[G^{n + 1}] \cong k[G] \otimes_k k[G^n].$ Also shows that given a $k$ -algebra $R$ and a $k$ -basis for a module $M,$ we get an $R$ -basis of $R \otimes_k M.$ Then, using that, we show $k[G^{n + 1}]$ is free.