@@ -146,11 +146,13 @@ theorem encard_le_coe_iff {k : ℕ} : s.encard ≤ k ↔ s.Finite ∧ ∃ (n₀
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section Lattice
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- theorem encard_le_card (h : s ⊆ t) : s.encard ≤ t.encard := by
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+ theorem encard_le_encard (h : s ⊆ t) : s.encard ≤ t.encard := by
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rw [← union_diff_cancel h, encard_union_eq disjoint_sdiff_right]; exact le_self_add
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+ @[deprecated (since := "2025-01-05")] alias encard_le_card := encard_le_encard
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+
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theorem encard_mono {α : Type *} : Monotone (encard : Set α → ℕ∞) :=
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- fun _ _ ↦ encard_le_card
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+ fun _ _ ↦ encard_le_encard
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theorem encard_diff_add_encard_of_subset (h : s ⊆ t) : (t \ s).encard + s.encard = t.encard := by
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rw [← encard_union_eq disjoint_sdiff_left, diff_union_self, union_eq_self_of_subset_right h]
@@ -235,7 +237,7 @@ theorem encard_insert_le (s : Set α) (x : α) : (insert x s).encard ≤ s.encar
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rw [← union_singleton, ← encard_singleton x]; apply encard_union_le
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theorem encard_singleton_inter (s : Set α) (x : α) : ({x} ∩ s).encard ≤ 1 := by
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- rw [← encard_singleton x]; exact encard_le_card inter_subset_left
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+ rw [← encard_singleton x]; exact encard_le_encard inter_subset_left
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theorem encard_diff_singleton_add_one (h : a ∈ s) :
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(s \ {a}).encard + 1 = s.encard := by
@@ -393,7 +395,7 @@ theorem encard_image_le (f : α → β) (s : Set α) : (f '' s).encard ≤ s.enc
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obtain (h | h) := isEmpty_or_nonempty α
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· rw [s.eq_empty_of_isEmpty]; simp
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rw [← (f.invFunOn_injOn_image s).encard_image]
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- apply encard_le_card
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+ apply encard_le_encard
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exact f.invFunOn_image_image_subset s
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theorem Finite.injOn_of_encard_image_eq (hs : s.Finite) (h : (f '' s).encard = s.encard) :
@@ -410,7 +412,7 @@ theorem encard_preimage_of_injective_subset_range (hf : f.Injective) (ht : t ⊆
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theorem encard_le_encard_of_injOn (hf : MapsTo f s t) (f_inj : InjOn f s) :
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s.encard ≤ t.encard := by
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- rw [← f_inj.encard_image]; apply encard_le_card ; rintro _ ⟨x, hx, rfl⟩; exact hf hx
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+ rw [← f_inj.encard_image]; apply encard_le_encard ; rintro _ ⟨x, hx, rfl⟩; exact hf hx
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theorem Finite.exists_injOn_of_encard_le [Nonempty β] {s : Set α} {t : Set β} (hs : s.Finite)
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(hle : s.encard ≤ t.encard) : ∃ (f : α → β), s ⊆ f ⁻¹' t ∧ InjOn f s := by
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