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[Merged by Bors] - feat(group_theory/subgroup) top is a normal subgroup #4982

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[Merged by Bors] - feat(group_theory/subgroup) top is a normal subgroup #4982

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a3a88b3
top is a normal subgroup
alexjbest Nov 11, 2020
32a7da1
shorter proof
alexjbest Nov 12, 2020
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3 changes: 3 additions & 0 deletions src/group_theory/subgroup.lean
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Expand Up @@ -747,6 +747,9 @@ end normal
@[priority 100, to_additive]
instance bot_normal : normal (⊥ : subgroup G) := ⟨by simp⟩

@[priority 100, to_additive]
instance top_normal : normal (⊤ : subgroup G) := ⟨λ _ _, mem_top⟩

variable (G)
/-- The center of a group `G` is the set of elements that commute with everything in `G` -/
@[to_additive "The center of a group `G` is the set of elements that commute with everything in `G`"]
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