We present an alternative and simpler method for computing principal typings
of flow networks. When limited to planar flow networks, the method can be made
to run in fixed-parameter linear-time -- where the parameter not to be exceeded
is what is called the edge-outerplanarity of the networks' underlying graphs.Comment: 12 pages, 0 figures, 13 references. arXiv admin note: text overlap
  with arXiv:1807.0418