27 lines
444 B
Lean4
27 lines
444 B
Lean4
import Game.Levels.LessOrEqual.L01le_refl
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World "LessOrEqual"
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Level 2
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Title "0 ≤ x"
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namespace MyNat
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Introduction
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"
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To solve this level, you need to `use` a number `c` such that `x = 0 + c`.
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"
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LemmaDoc MyNat.zero_le as "zero_le" in "≤" "
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`zero_le x` is a proof that `0 ≤ x`.
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"
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NewLemma MyNat.zero_le
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/-- If $x$ is a number, then $0 \le x$. -/
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Statement zero_le (x : ℕ) : 0 ≤ x := by
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use x
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rw [zero_add]
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rfl
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LemmaTab "≤"
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