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theorem proved term proof

one_sub_phi_inv_eq_phi_inv_sq

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formal statement (Lean)

  50theorem one_sub_phi_inv_eq_phi_inv_sq : 1 - phi⁻¹ = phi⁻¹ ^ 2 := by

proof body

Term-mode proof.

  51  have hphi : phi ≠ 0 := phi_ne_zero
  52  have hphi_sq : phi ^ 2 = phi + 1 := phi_sq_eq
  53  field_simp [hphi]
  54  nlinarith [sq_pos_of_pos phi_pos, hphi_sq]
  55
  56/-- The two band boundaries sum to one. -/

depends on (11)

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