The generalized Grassmann–Plücker exchange conjecture for matroid bases

Let AA and BB be bases of a matroid M\mathbf{M} with rank function rr. For any XABX\subseteq A\setminus B and YBAY\subseteq B\setminus A and integer pp with YpX|Y| \le p \le |X|, there should exist UABU \subseteq A\setminus B and VBAV \subseteq B\setminus A such that

UX=p,YV,U=Vr((UX)Y),|U\cap X|=p,\qquad Y\subseteq V,\qquad |U|=|V|\le r((U\cap X)\cup Y),

and AUVA\setminus U\cup V and BUVB\cup U\setminus V are bases. Generalized Grassmann–Plücker exchange conjecture. The stated exchange property holds for every matroid. This would provide a common generalization of the paper's equitability-exchange theorem and its main theorem: it recovers the latter when p=Xp=|X| and specializes to the former, with additional upper bounds on U|U| and V|V|, when p=X1Yp=|X|-1\ge |Y|.

Sources & referencesView supporting material

Primary source

Taihei Oki and Tamás Schwarcz, “Generalizing the Multiple Exchange Property for Matroid Bases”, arXiv:2511.16021 (2026).

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