Question: Suppose our definition of a network is relaxed so as to allow arcs to enter the source and/or leave the sink; now the volume of a flow x is properly defined as
![761_SJ.png](https://secure.tutorsglobe.com/CMSImages/761_SJ.png)
In this generalized context, prove that for every feasible flow of volume v there is a feasible flow x of volume at least v such that Xis = 0 for all arcs is entering the source and xij = 0 for all arcs tj leaving the sink. What is the significance of this observation?