15 lines
233 B
Text
15 lines
233 B
Text
a b : ℕ
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⊢ 0 + 0 + b + 0 = b
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a b : ℕ,
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H : a + 0 + 0 = b
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⊢ b = a
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a : ℕ
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⊢ a + (0 + a) + a = a + a + a
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a : ℕ
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⊢ 0 + a + a + (0 + a) = a + a + a
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a : ℕ
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⊢ 0 + a + a + a = a + a + a
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