We start with "cographic multiflows," a basic special case of "matroid flow problem," exhaustively studied in Seymour's celebrated paper, "Matroids and multicommodity flows." This special case is closely related to matching theory and contains also the edge-disjoint paths problem in graphs still planar after adding the "demand couples" as edges. M. Middendorf and F.Pfeiffer have proved recently that this latter problem is NP-complete, closing the cographic multiflow problem in some sense.
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机译：我们从“摄影多流”开始，这是“类胶体流动问题”的基本特殊情况，在西摩著名论文《类人动物和多商品流》中进行了详尽的研究。这种特殊情况与匹配理论密切相关，并且在添加“需求对”作为边后，在仍然为平面的图中还包含边不相交的路径问题。 M. Middendorf和F.Pfeiffer最近证明了后一个问题是NP完全问题，从某种意义上解决了地形多流问题。
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