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theorem proved term proof

two_rotations

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formal statement (Lean)

  84theorem two_rotations :
  85    cexp (I * Real.pi / 2) * cexp (I * Real.pi / 2) = cexp (I * Real.pi) := by

proof body

Term-mode proof.

  86  rw [← Complex.exp_add]
  87  ring_nf
  88
  89/-- **THEOREM**: i² = -1 follows from 8-tick phase structure.
  90
  91    i = e^{iπ/2} (2 ticks from 1)
  92    i² = e^{iπ} = -1 (4 ticks from 1) -/

depends on (5)

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