lemma
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term proof
exp_0481_lt_phi
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232private lemma exp_0481_lt_phi : exp_taylor_10_at_0481 + exp_error_10_at_0481 < 161803395 / 100000000 := by
proof body
Term-mode proof.
233 native_decide
234
235/-- Rigorous lower bound: log(φ) > 0.481.
236
237 Proof using exp monotonicity: log(φ) > 0.481 ↔ φ > exp(0.481).
238 We have φ > 1.61803395 and exp(0.481) ≈ 1.617691... < 1.61803395. -/