theorem cascade_long_run_zero {lam mu : ℝ} (hlam : 0 < lam) (hmu : 0 < mu) :
Filter.Tendsto (fun h : ℝ => Real.exp (-mu * h) - Real.exp (-lam * h))
Filter.atTop (nhds 0) := by
have key : ∀ c : ℝ, 0 < c →
Filter.Tendsto (fun h : ℝ => Real.exp (-c * h)) Filter.atTop (nhds 0) := by
intro c hc
have h1 := Real.tendsto_exp_neg_atTop_nhds_zero.comp
(Filter.Tendsto.const_mul_atTop hc Filter.tendsto_id)
convert h1 using 1
funext h; simp [neg_mul, id]
have hsub := (key mu hmu).sub (key lam hlam)
simp only [sub_self] at hsub
exact hsubProposition 6, Theorem 9, Corollaries 1-2 and 4: