Multiuser information theory has been an important research area since the 1970â„¢s. In the past few years, there has been a surge in research activities in the area due to its potential applications to communication networks. In particular, the recent theory of network coding reveals the surprising fact that unlike what was believed in the past, information should not be regarded as a commodity in a network. Since its inception, network coding has emerged as a new paradigm that has influenced information and coding theory, networking, wireless communications, computer science, graph theory, and matrix theory