theorem
proved
tactic proof
J_bit_eq_phi_minus
show as:
view Lean formalization →
formal statement (Lean)
88theorem J_bit_eq_phi_minus : J_bit_val = phi - 3/2 := by
proof body
Tactic-mode proof.
89 unfold J_bit_val J
90 -- Key identity: 1/φ = φ - 1 (from φ² = φ + 1)
91 have h_inv : phi⁻¹ = phi - 1 := by
92 have hphi_ne : phi ≠ 0 := phi_pos.ne'
93 have hsq : phi^2 = phi + 1 := phi_sq_eq
94 have : phi * phi = phi + 1 := by rw [← sq]; exact hsq
95 field_simp at this ⊢
96 linarith
97 rw [h_inv]
98 ring
99
100/-- **Numerical Bound**: J_bit ≈ 0.118.
101 Since 1.61 < φ < 1.62, we have 0.11 < J_bit < 0.12. -/