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[Merged by Bors] - feat(GroupTheory/Subgroup/Basic): ker_{fst,snd} #6639
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pechersky
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Aug 17, 2023
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bors d+
Thanks! Some golfs to consider
✌️ pechersky can now approve this pull request. To approve and merge a pull request, simply reply with |
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
@@ -2887,6 +2887,12 @@ instance (priority := 100) normal_ker (f : G →* M) : f.ker.Normal := | |||
#align monoid_hom.normal_ker MonoidHom.normal_ker | |||
#align add_monoid_hom.normal_ker AddMonoidHom.normal_ker | |||
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@[to_additive (attr := simp)] | |||
lemma ker_fst : ker (fst G G') = (.prod ⊥ ⊤) := ext fun _ => (and_true_iff _).symm |
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Whoops, I guess this wasn't the namespace I thought it was
lemma ker_fst : ker (fst G G') = (.prod ⊥ ⊤) := ext fun _ => (and_true_iff _).symm | |
lemma ker_fst : ker (fst G G') = (.prod ⊥ ⊤) := SetLike.ext fun _ => (and_true_iff _).symm |
bors r+ |
Co-authored-by: Yakov Pechersky <pechersky@users.noreply.github.com> Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
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