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chore(Topology/Compactness/CountablyCompact): generalize theorem (leanprover-community#39600)
Generalize theorem `Topology.IsEmbedding.isSeqCompact_iff` to `Topology.IsInducing.isSeqCompact_iff` by replacing `IsEmbedding` by `IsInducing`. Also fix capitalization error.
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Mathlib/Topology/Compactness/CountablyCompact.lean

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@@ -261,9 +261,9 @@ instance (priority := 50) [SequentialSpace E] [CountablyCompactSpace E] :
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· simp only [image_eq_iUnion, mem_Ici, iUnion_ge_eq_iUnion_nat_add _ (k + 1)]
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exact iUnion_mono fun i => subset_closure
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/-- If `f : X → Y` is an embedding map, the image `f '' s` of a set `s` is sequentially compact
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/-- If `f : X → Y` is an inducing map, the image `f '' s` of a set `s` is sequentially compact
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if and only if `s` is sequentially compact. -/
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theorem Topology.IsEmbedding.isSeqCompact_iff {f : E → F} (hf : IsEmbedding f) :
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theorem Topology.IsInducing.isSeqCompact_iff {f : E → F} (hf : IsInducing f) :
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IsSeqCompact A ↔ IsSeqCompact (f '' A) where
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mp hA x hx := by
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choose y hy using hx
@@ -358,10 +358,13 @@ theorem IsLindelof.isCompact (hA : IsCountablyCompact A) (hl : IsLindelof A) :
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· exact ⟨∅, by simp_all⟩
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/-- A countably compact Lindelöf space is compact. -/
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theorem LindelofSpace.CompactSpace {X : Type*} [TopologicalSpace X]
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theorem LindelofSpace.compactSpace {X : Type*} [TopologicalSpace X]
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[LindelofSpace X] [h : CountablyCompactSpace X] : CompactSpace X where
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isCompact_univ := isLindelof_univ.isCompact h.isCountablyCompact_univ
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@[deprecated (since := "2026-05-19")]
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alias LindelofSpace.CompactSpace := LindelofSpace.compactSpace
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/-- In a Hereditarily Lindelöf space, a countably compact set is compact. -/
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theorem IsCountablyCompact.isCompact [HereditarilyLindelofSpace E]
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(hA : IsCountablyCompact A) : IsCompact A :=

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