lemma
proved
tactic proof
log2_succ_le
show as:
view Lean formalization →
formal statement (Lean)
96private lemma log2_succ_le (n : Nat) : Nat.log2 n.succ ≤ n := by
proof body
Tactic-mode proof.
97 rw [Nat.log2_eq_log_two]
98 have h1 : 1 < 2 := by norm_num
99 have h3 : n.succ ≠ 0 := by omega
100 have hlt : Nat.log 2 n.succ < n.succ := by
101 rw [Nat.log_lt_iff_lt_pow h1 h3]
102 have h4 : n.succ.succ ≤ 2^n.succ := succ_le_two_pow n.succ
103 calc n.succ < n.succ.succ := by omega
104 _ ≤ 2 ^ n.succ := h4
105 omega
106
107/-- maxOctantLevel n ≤ n (since log2(n+1)/3 ≤ log2(n+1) ≤ n). -/