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We prove that a binary matroid with huge branch-width contains the cycle matroid of a large grid as a minor. This implies that an infinite antichain of binary matroids cannot contain the cycle matroid of a planar graph. The result also holds for any other finite field.
Let $A$ be the edge-node incidence matrix of a bipartite graph $G = (U, V ; E)$, $I$ be a subset of the nodes of $G$, and $b$ be a vector such that $2b$ is integral. We consider the following mixed-integer set: $X(G, b, I) = {x : Ax ≥ b, x ≥ 0, x_i$ integer for all $i ∈ I}$
This paper surveys recent work that is aimed at generalising the results and techniques of the Graph Minors Project of Robertson and Seymour to matroids.
We determine the structure of a class of graphs that do not contain the complete graph on five vertices as a “signed minor.” The result says that each graph in this class can be decomposed into elementary building blocks in which maximum packings by odd circuits can be found by flow or m
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