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32 lines
434 B
Plaintext
32 lines
434 B
Plaintext
import NNG.Metadata
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import NNG.MyNat.Addition
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import Std.Tactic.RCases
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Game "NNG"
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World "AdvProposition"
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Level 4
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Title ""
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open MyNat
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Introduction
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"
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"
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Statement iff_trans
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""
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(P Q R : Prop) : (P ↔ Q) → (Q ↔ R) → (P ↔ R) := by
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intro hpq
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intro hqr
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rcases hpq with ⟨hpq, hqp⟩
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rcases hqr with ⟨hqr, hrq⟩
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constructor
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exact fun x => hqr (hpq x) -- cc
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exact fun x => hqp (hrq x) -- cc
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Conclusion
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"
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"
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