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We introduce the active partition of the ground set of an oriented matroid perspective (or quotient, or strong map) on a linearly ordered ground set. The reorientations obtained by arbitrarily reorienting parts of the active partition share…

Combinatorics · Mathematics 2018-07-19 Emeric Gioan

The weighted transition polynomial of a multimatroid is a generalization of the Tutte polynomial. By defining the activity of a skew class with respect to a basis in a multimatroid, we obtain an activities expansion for the weighted…

Combinatorics · Mathematics 2025-02-24 Criel Merino , Iain Moffatt , Steven Noble

In this note we generalize the convolution formula for the Tutte polynomial of Kook-Reiner-Stanton and Etienne-Las Vergnas to a more general setting that includes both arithmetic matroids and delta-matroids. As corollaries, we obtain new…

Combinatorics · Mathematics 2017-04-24 Spencer Backman , Matthias Lenz

We introduce and study filtrations of a matroid on a linearly ordered ground set, which are particular sequences of nested sets. A given basis can be decomposed into a uniquely defined sequence of bases of minors, such that these bases have…

Combinatorics · Mathematics 2018-07-19 Emeric Gioan , Michel Las Vergnas

We recover the Tutte polynomial of a matroid, up to change of coordinates, from an Ehrhart-style polynomial counting lattice points in the Minkowski sum of its base polytope and scalings of simplices. Our polynomial has coefficients of…

Combinatorics · Mathematics 2018-02-28 Amanda Cameron , Alex Fink

$q$-Matroids are defined on complemented modular support lattices. Minors of length 2 are of four types as in a "classical" matroid. Tutte polynomials $\tau(x,y)$ of matroids are calculated either by recursion over deletion/contraction of…

Combinatorics · Mathematics 2017-07-13 Guus Bollen , Henry Crapo , Relinde Jurrius

The Tutte polynomial is the most general invariant of matroids and graphs that can be computed recursively by deleting and contracting edges. We generalize this invariant to any class of combinatorial objects with deletion and contraction…

Combinatorics · Mathematics 2019-02-04 Clément Dupont , Alex Fink , Luca Moci

We use the equivariant cohomology ring of the permutohedral variety to study matroids and their invariants. Investigating the pushforward of matroid Chern classes defined by A. Berget, C. Eur, H. Spink and D. Tseng to the product space…

Algebraic Geometry · Mathematics 2025-09-25 Mario Bauer , Matěj Doležálek , Magdaléna Mišinová , Semen Słobodianiuk , Julian Weigert

By considering Tutte polynomials of Hopf algebras, we show how a Tutte polynomial can be canonically associated with combinatorial objects that have some notions of deletion and contraction. We show that several graph polynomials from the…

Combinatorics · Mathematics 2018-03-01 Thomas Krajewski , Iain Moffatt , Adrian Tanasa

The active bijection for oriented matroids (and real hyperplane arrangements, and graphs, as particular cases) is introduced and investigated by the authors in a series of papers. Given any oriented matroid defined on a linearly ordered…

Combinatorics · Mathematics 2018-07-19 Emeric Gioan , Michel Las Vergnas

The Tutte polynomial is a significant invariant of graphs and matroids. It is well-known that it has three equivalent definitions: bases expansion, rank generating function, and deletion-contraction formula. The polymatroid Tutte polynomial…

Combinatorics · Mathematics 2025-10-14 Xiaxia Guan , Xian'an Jin , Weiling Yang

The multiplicity Tutte polynomial, which includes the arithmetic Tutte polynomial, is a generalization of the classical Tutte polynomial of matroids. In this paper, we obtain an expression of the general coefficient and the expressions of…

Combinatorics · Mathematics 2024-02-06 Xian'an Jin , Tianlong Ma , Weiling Yang

We generalize theories of graph, matroid, and ribbon-graph activities to delta-matroids. As a result, we obtain an activities based feasible-set expansion for a transition polynomial of delta-matroids defined by Brijder and Hoogeboom. This…

Combinatorics · Mathematics 2017-10-31 Ada Morse

The Tutte equations are ported (or set-pointed) when the equations F(N) = g_e F(N/e) + r_e F(N\e) are omitted for elements e in a distinguished set called ports. Solutions F can distinguish different orientations of the same matroid. A…

Combinatorics · Mathematics 2007-05-23 Seth Chaiken

We introduce the Schubert variety of a pair of linear subspaces in $\mathbf{C}^n$ and the external activity complex of a pair of not necessarily realizable matroids. Both of these generalize constructions of Ardila et al., which occur when…

Combinatorics · Mathematics 2025-03-26 Andrew Berget , Alex Fink

Unlike Whitney's definition of the corank-nullity generating function $T(G;x+1,y+1)$, Tutte's definition of his now eponymous polynomial $T(G;x,y)$ requires a total order on the edges of which the polynomial is a posteriori independent.…

Combinatorics · Mathematics 2019-06-11 Spencer Backman

The Tutte polynomial is a crucial invariant of matroids. The polymatroid Tutte polynomial $\mathscr{T}_{P}(x,y)$, introduced by Bernardi et al., is an extension of the classical Tutte polynomial from matroids to polymatroids $P$. In this…

Combinatorics · Mathematics 2023-09-26 Xiaxia Guan , Xian'an Jin , Tamás Kálmán

The surface Tutte polynomial has recently been generalised to pseudo-surfaces equipping it with recursive deletion-contraction relations. We use these relations to show that this generalisation naturally possesses a quasi-tree expansion.…

Combinatorics · Mathematics 2025-06-17 Maya Thompson

Lop\'ez de Medrano-Rin\'con-Shaw defined Chern-Schwartz-MacPherson cycles for an arbitrary matroid $M$ and proved by an inductive geometric argument that the unsigned degrees of these cycles agree with the coefficients of $T(M;x,0)$, where…

Combinatorics · Mathematics 2022-07-21 Ahmed Umer Ashraf , Spencer Backman

Specializing the $\gamma$-basis for the vector space $\mathcal{G}(n,r)$ spanned by the set of symbols on bit sequences with $r$ $1$'s and $n-r$ $0$'s, we obtain a frame or spanning set for the vector space $\mathcal{T}(n,r)$ spanned by…

Combinatorics · Mathematics 2021-06-08 Joseph P. S. Kung
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