31 lines
511 B
Lean4
31 lines
511 B
Lean4
import Game.Levels.AdvAddition.Level_10
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Game "NNG"
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World "AdvAddition"
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Level 11
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Title "add_right_eq_zero"
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open MyNat
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Introduction
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"
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We just proved `add_left_eq_zero (a b : ℕ) : a + b = 0 → b = 0`.
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Hopefully `add_right_eq_zero` shouldn't be too hard now.
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"
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Statement MyNat.add_right_eq_zero
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"If $a$ and $b$ are natural numbers such that
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$$ a + b = 0, $$
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then $a = 0$."
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{a b : ℕ} : a + b = 0 → a = 0 := by
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intro h
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rw [add_comm] at h
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exact add_left_eq_zero h
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LemmaTab "Add"
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Conclusion
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"
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"
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