9 lines
264 B
Text
9 lines
264 B
Text
open nat
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protected theorem one_le_bit0 (n : ℕ) : n ≠ 0 → 1 ≤ bit0 n :=
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nat.cases_on n
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(λ h, absurd rfl h)
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(λ n h,
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suffices 1 ≤ succ (succ (bit0 n)), from
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eq.symm (nat.bit0_succ_eq n) ▸ this,
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succ_le_succ (zero_le (succ (bit0 n))))
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