These notes provide an introduction to and proof of Lemma 2.5.
Lemma 2.5: When M ≥ p ≥ -U and α and Ω are fixed finite values satisfying α < Ω, the average cost of the (s, S) policy (α, Ω) 
is unimodal in the drift rate u.
Download the pdf or read with the interactive figures here.
