Date Added: Nov 2012
The notion of Network Coding was introduced in where the capacity of wireline multicast networks is characterized. Scalar linear network coding was found to achieve the capacity of multicast networks. In the meanwhile, it was shown that there exist solvable non-multicast networks where scalar linear network coding is insufficient. In addition, also showed that determining the existence of linear network coding solution for multiple unicast networks is NP-hard in general. In, it was conjectured that vector linear network coding suffices to solve networks with arbitrary message demands. Subsequently, Dogherty et al.