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Flag matroids are combinatorial abstractions of flags of linear subspaces, just as matroids are of linear subspaces. We introduce the flag Dressian as a tropical analogue of the partial flag variety, and prove a correspondence between: (a)…

Combinatorics · Mathematics 2021-03-08 Madeline Brandt , Christopher Eur , Leon Zhang

We use the Strong Splitter Theorem to decompose the excluded minor class of binary matroids with no $E_4$-minor. Using this theorem we can get the 3-decomposers and the extremal internally 4-connected matroids as well as any other important…

Combinatorics · Mathematics 2014-08-12 S. R. Kingan

Multimatroids generalize matroids, delta-matroids, and isotropic systems, and transition polynomials of multimatroids subsume various polynomials for these latter combinatorial structures, such as the interlace polynomial and the…

Combinatorics · Mathematics 2017-08-18 Robert Brijder

The notion of thin sums matroids was invented to extend the notion of representability to non-finitary matroids. A matroid is tame if every circuit-cocircuit intersection is finite. We prove that a tame matroid is a thin sums matroid over a…

Combinatorics · Mathematics 2012-12-18 Nathan Bowler , Johannes Carmesin

Matrix partition problems generalize a number of natural graph partition problems, and have been studied for several standard graph classes. We prove that each matrix partition problem has only finitely many minimal obstructions for split…

Discrete Mathematics · Computer Science 2013-06-21 Tomás Feder , Pavol Hell , Oren Shklarsky

We present infinite sequences of excluded minors for both the class of lifted-graphic matroids and the class of frame matroids.

Combinatorics · Mathematics 2018-04-19 Rong Chen , Jim Geelen

The introduction of covering-based rough sets has made a substantial contribution to the classical rough sets. However, many vital problems in rough sets, including attribution reduction, are NP-hard and therefore the algorithms for solving…

Artificial Intelligence · Computer Science 2013-11-06 Bin Yang , Hong Zhao , William Zhu

At present, practical application and theoretical discussion of rough sets are two hot problems in computer science. The core concepts of rough set theory are upper and lower approximation operators based on equivalence relations. Matroid,…

Artificial Intelligence · Computer Science 2012-09-26 Lirun Su , William Zhu

In this thesis, we study nearly finitary matroids by introducing new definitions and prove various properties of nearly finitary matroids. In 2010, an axiom system for infinite matroids was proposed by Bruhn et al. We use this axiom system…

Combinatorics · Mathematics 2019-06-13 Patrick Tam

Matroids are often represented as oracles since there are no unified and compact representations for general matroids. This paper initiates the study of binary decision diagrams (BDDs) and zero-suppressed binary decision diagrams (ZDDs) as…

Combinatorics · Mathematics 2024-04-24 Hiromi Emoto , Yuni Iwamasa , Shin-ichi Minato

The structure of zero and nonzero minors in the Grassmannian leads to rich combinatorics of matroids. In this paper, we investigate an even richer structure of possible equalities and inequalities between the minors in the positive…

Combinatorics · Mathematics 2015-09-10 Miriam Farber , Yelena Mandelshtam

Matroid theory provides a unifying framework for studying dependence across combinatorics, geometry, and applications ranging from rigidity to statistics. In this work, we study circuit varieties of matroids, defined by their minimal…

Combinatorics · Mathematics 2025-12-05 Emiliano Liwski , Fatemeh Mohammadi , Rémi Prébet

Let $M$ be an arbitrary matroid with circuits $\mathcal{C}(M)$. We propose a definition of a derived matroid $\delta M$ that has as its ground set $\mathcal{C}(M)$. Unlike previous attempts of such a definition, our definition applies to…

Combinatorics · Mathematics 2022-12-22 Olga Kuznetsova , Ragnar Freij-Hollanti , Relinde Jurrius

In mathematics and computer science, connectivity is one of the basic concepts of matroid theory: it asks for the minimum number of elements which need to be removed to disconnect the remaining nodes from each other. It is closely related…

Artificial Intelligence · Computer Science 2013-11-06 Bin Yang , William Zhu

There is a long list of open questions rooted in the same underlying problem: understanding the structure of bases or common bases of matroids. These conjectures suggest that matroids may possess much stronger structural properties than are…

Combinatorics · Mathematics 2024-11-05 Kristóf Bérczi , Áron Jánosik , Bence Mátravölgyi

Delta-matroid theory is often thought of as a generalization of topological graph theory. It is well-known that an orientable embedded graph is bipartite if and only if its Petrie dual is orientable. In this paper, we first introduce the…

Combinatorics · Mathematics 2020-03-05 Qi Yan , Xian'an Jin

We make progress towards characterizing the algebraic matroid of the determinantal variety defined by the minors of fixed size of a matrix of variables. Our main result is a novel family of base sets of the matroid, which characterizes the…

Algebraic Geometry · Mathematics 2023-02-24 Manolis C. Tsakiris

We present a formal analysis, in Isabelle/HOL, of optimisation algorithms for matroids, which are useful generalisations of combinatorial structures that occur in optimisation, and greedoids, which are a generalisation of matroids. Although…

Logic in Computer Science · Computer Science 2025-07-01 Mohammad Abdulaziz , Thomas Ammer , Shriya Meenakshisundaram , Adem Rimpapa

We prove that for every proper minor-closed class $M$ of matroids representable over a prime field, there exists a constant-competitive matroid secretary algorithm for the matroids in $M$. This result relies on the extremely powerful…

Combinatorics · Mathematics 2019-10-03 Tony Huynh , Peter Nelson

In this paper we introduce valuated $\Delta$-matroids, a natural generalization of two objects of study in matroid theory: valuated matroids and $\Delta$-matroids. We show that these objects exhibit nice properties analogous to ordinary…

Combinatorics · Mathematics 2025-07-23 Nathan Cheung , Tracy Chin , Gaku Liu , Cynthia Vinzant