Yeah, I'm clueless, to be honest.
I'd really appreciate a little help with my transportation problem and finding its optimal solution.
Supply and demand werent equal in the initial table (demand > supply by 20 units), so I adjusted demand accordingly for it to match supply (basically by decreasing each of the consumers demand by 5). Then I solved the problem using Vogel's method.
Problem is, when I start checking for optimality (using potentials method u1 + v1 = Cij for any filled route), I get that the initial solution is the optimal solution (opportunity cost (= Cij - u1 - v1) for nonfilled routes is in all cases non-negative).
I must be doing something wrong, as I know the solution can't be optimal. For example, solving the problem with Vogel's method by creating a fictive supplier to equalize demand and supply results in a much lower transportation cost solution...
Help would be greatly appreciated!