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lean4game/server/adam/Adam/Levels/SetTheory/L05_Empty.lean

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import Adam.Metadata
import Adam.Levels.SetTheory.L04_SubsetEmpty
--import Mathlib.Data.Set.Basic
import Mathlib.Init.Set
import Mathlib.Tactic.Tauto
import Mathlib.Tactic.PushNeg
set_option tactic.hygienic false
Game "Adam"
World "SetTheory"
Level 5
Title "Empty"
Introduction
"
Zeige folgendes Lemma, welches wir gleich brauchen werden:
"
open Set
Statement Set.eq_empty_iff_forall_not_mem
""
{A : Type _} (s : Set A) :
s = ∅ ↔ ∀ x, x ∉ s := by
Hint "Das Lemma `subset_empty_iff` von letzter Aufgabe könnte hilfreich sein."
rw [←subset_empty_iff]
rfl -- This is quite a miracle :)
NewTactic constructor intro rw assumption rcases simp tauto trivial
NewLemma Set.subset_empty_iff
LemmaTab "Set"