theorem herfindahl_merger_max_at_equal_split {s : ℝ} (hs : 0 < s)
{a_i : ℝ} (ha_i : 0 < a_i) (ha_lt : a_i < s) :
2 * a_i * (s - a_i) ≤ s ^ 2 / 2 := by
nlinarith [sq_nonneg (a_i - s / 2)]Herfindahl Dynamics: Entry, Exit, and Merger Effects on Concentration