theorem phieff_ge_one_condition {phi_0 beta_auto : ℝ}
(_hphi : 0 < phi_0) (_hbeta : 0 < beta_auto)
(hbeta_le : beta_auto ≤ 1)
(hprod : beta_auto * phi_0 < 1)
(hhalf : 1 / 2 ≤ beta_auto * phi_0) :
1 ≤ effectiveTrainingProductivity phi_0 beta_auto := by
unfold effectiveTrainingProductivity
have hdenom_pos : 0 < 1 - beta_auto * phi_0 := by linarith
rw [le_div_iff₀ hdenom_pos]
nlinarith [mul_le_of_le_one_left (by linarith : 0 ≤ phi_0) hbeta_le]Paper 6: Endogenous Decentralization and the AI Transition