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lean4game/server/nng/NNG/Levels/AdvProposition/Level_9.lean

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import NNG.Metadata
import NNG.MyNat.Addition
import Std.Tactic.RCases
import NNG.MyNat.Theorems.Proposition
Game "NNG"
World "AdvProposition"
Level 9
Title ""
open MyNat
Introduction
"
"
Statement contra
""
(P Q : Prop) : (P ∧ ¬ P) → Q := by
intro h
rcases h with ⟨p, np ⟩
contradiction
-- rw [not_iff_imp_false] at np
-- exfalso
-- apply np
-- exact p
NewTactic exfalso contradiction
Conclusion
"
"