Matroid matching with Dilworth truncation

Abstract

Let $H=(V,E)$ be a hypergraph and let $k≥ 1$ and$ l≥ 0$ be fixed integers. Let $\mathcal{M}$ be the matroid with ground-set $E s.t. a$ set $F⊆E$ is independent if and only if each $X⊆V$ with $k|X|-l≥ 0$ spans at most $k|X|-l$ hyperedges of $F$. We prove that if $H$ is dense enough, then $\mathcal{M}$ satisfies the double circuit property, thus the min-max formula of Dress and Lovász on the maximum matroid matching holds for $\mathcal{M}$ . Our result implies the Berge-Tutte formula on the maximum matching of graphs $(k=1, l=0)$, generalizes Lovász' graphic matroid (cycle matroid) matching formula to hypergraphs $(k=l=1)$ and gives a min-max formula for the maximum matroid matching in the 2-dimensional rigidity matroid $(k=2, l=3)$.