Probability and Stochastic Processes

Sampling from a Stream

Selecting a random element from an array of length n is easy: simply generate a random integer i, with 0 <= i < n, and use the array element at that index position. But what if the length of the array is not known beforehand, or is, in fact, infinite (i.e. a stream)? And what if we don’t just want a single element, but a set of m samples, without replacement?

The Newsvendor Problem

The “Newsvendor Problem” is a classic problem in inventory and supply-chain management: how much product to carry in stock in the face of uncertain demand?

The problem is obviously of interest in its own right, but it is also an archetypical problem, meaning that variations of it arise frequently and in different contexts. It is therefore valuable to know “how to think about” this kind of problem; in particular, since in its simplest form, it has a closed-form, analytic solution.