Isotropic Matroids I: Multimatroids and Neighborhoods

  • Robert Brijder
  • Lorenzo Traldi
Keywords: Delta-matroid, Interlacement, Isotropic system, Local equivalence, Matroid, Multimatroid, Stable set


Several properties of the isotropic matroid of a looped simple graph are presented. Results include a characterization of the multimatroids that are associated with isotropic matroids and several ways in which the isotropic matroid of $G$ incorporates information about graphs locally equivalent to $G$. Specific results of the latter type include a characterization of graphs that are locally equivalent to bipartite graphs, a direct proof that two forests are isomorphic if and only if their isotropic matroids are isomorphic, and a way to express local equivalence indirectly, using only edge pivots.

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