the action costs. Examples also illustrate the involved performance trade-offs across the network.'
author:
- 'Behzad Ahmadi, Chiranjib Choudhuri, Osvaldo Simeone and Urbashi Mitra [^1][^2]'
title: 'Cascade Source Coding with a Side Information “Vending Machine”'
---

Rate-distortion theory, cascade source coding, side information, vending machine, common reconstruction constraint.

Introduction
============

The concept of a side information “vending machine (VM) was introduced in [@Permuter] for a point-to-point model, in order to account for source coding scenarios in which acquiring the side information at the receiver entails some cost and thus should be done efficiently. In this class of models, the quality of the side information $Y$ can be controlled at the decoder by selecting an action $A$ that affects the effective channel between the source $X$ and the side information $Y$ through a conditional distribution $p_{Y|X,A}(y|x,a)$. Each action $A$ is associated with a cost, and the problem is that of characterizing the available trade-offs between rate, distortion and action cost.

Extending the point-to-point set-up, cascade models provide baseline scenarios in which to study fundamental aspects of communication in multi-hop networks, which are central to the operation of, e.g., sensor or computer networks (see Fig. \[fig:fig1\]). Standard information-theoretic models for cascade scenarios 