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LeanPool.NairTenenbaum.DivisorSums.PrimeFactorLogGain

Quantitative logarithmic gain from saved prime factors #

The error in a lower bound for the rough logarithmic mass must be smaller than the saving from divisor hits. A merely qualitative o(1) relative error does not supply the quantitative conclusion used in Theorem 2.

theorem NairTenenbaum.exp_gain_of_logMass_bounds {P y a H E M : ℝ} (hP : 1 ≤ P) (hy : 1 ≤ y) (ha : 0 < a) (hH : 0 ≤ H) (hHa : H ≤ a) (hlower : a * Real.log y - E ≤ M) (hupper : M ≤ (a - H) * Real.log P) (herror : E ≤ H * Real.log y / 2) :
y * Real.exp (H * Real.log y / (2 * a)) ≤ P

Convert logarithmic mass and a factor-count saving into an exponential lower bound. E is the absolute error in the mass estimate.