Level cap, general form: log ratio bounded by level exponent
Provedgpy_log_ratio_lt_of_levelnumber-theory
A level constraint R^2 < Y'^(theta - eta) with Y' > 1 caps the sieve log ratio log R / log Y' at theta/2 - eta/2. Pure Mathlib statement.
Preamble
import Mathlib open Classical
Formal statement
theorem gpy_log_ratio_lt_of_level {R Y' : ℕ} {θ η : ℝ}
(hR : 2 ≤ R) (hY : 1 < Y')
(hlev : (R : ℝ) ^ 2 < (Y' : ℝ) ^ (θ - η)) :
Real.log (R : ℝ) / Real.log (Y' : ℝ) < θ / 2 - η / 2 := by sorrySource
GPY ratio analysis: threshold, main-term approximations, and BV level cap