The matroidal Merino–Welsh conjectures

Let MM be a matroid without loops or coloops, and let T(M;x,y)T(M;x,y) be its Tutte polynomial. Matroidal Merino–Welsh conjectures. The following inequalities hold:

max(T(M;2,0),T(M;0,2))T(M;1,1),\max\left(T(M;2,0),T(M;0,2)\right)\geq T(M;1,1), T(M;2,0)+T(M;0,2)2T(M;1,1),T(M;2,0)+T(M;0,2)\geq 2\cdot T(M;1,1),

and

T(M;2,0)T(M;0,2)T(M;1,1)2.T(M;2,0)\cdot T(M;0,2)\geq T(M;1,1)^2.

These conjectures generalize the graphic inequalities through the Tutte-polynomial interpretations of spanning trees and orientations. The first inequality is known for paving matroids, Catalan matroids, and whirls, while the paper proves the multiplicative conjecture for lattice path matroids; the general matroidal conjectures remain open.

Sources & referencesView supporting material

Primary source

Kolja Knauer, Leonardo Martínez-Sandoval and Jorge Luis Ramírez Alfonsín, “A Tutte polynomial inequality for lattice path matroids”, arXiv:1510.00600 (2016).

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