Four‐terminus flows
Paul D. Seymour · Networks · 1980
Abstract Suppose that s1, s2, s3, s4 are vertices of a graph, that each edge has a real‐valued capacity, and qii(1 ⩽ i < j ⩽ 4) are six demands. There exist flows from si to sj of value qij(1 ⩽ i < j ⩽ 4), such that the total flow through each edge does not exceed its capacity, if and only if the obvious connectivity requirements are satisfied. This result extends Hu's 2‐commodity flow theorem.