We consider the maximum integral tWo-Commodity flow problem in augmented planar graphs (i.e., with both source-sink edges added) and provide an o(IVI 2 1ogIVI) algorithm for that problem. Let G = (V, E) be a graph and w : E-t Z+ a weight function. Let T C V be an even subset of the vertices of G. A T-cut is an edge-cutset of the graph which divides T into two odd sets. Lomonosov gave a good cha...

Models of economic geography predict that transportation costs directly affect demand for goods and the supply of intermediate inputs. One of the reasons that international trade is concentrated in the coastal provinces of China is that they have lower transportation costs in transporting goods to other countries than do provinces in the interior. This paper examines the relationship between th...

Economic interactions are conducted between economic agents individuals and collectives, through exchange of natural or artificial entities goods, services and money, in a myriad of combinations. In this article we adopt a microscopic point of view, concentrating on the exchanged entities, and extracting their relevant attributes as seen from structurally simple economic processes. Following th...