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arXiv · 1907.13343

Fractal classes of matroids

Dillon Mayhew·Mike Newman·Geoff Whittle
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Abstract

A minor-closed class of matroids is (strongly) fractal if the number of n-element matroids in the class is dominated by the number of n-element excluded minors. We conjecture that when K is an infinite field, the class of K-representable matroids is strongly fractal. We prove that the class of sparse paving matroids with at most k circuit-hyperplanes is a strongly fractal class when k is at least three. The minor-closure of the class of spikes with at most k circuit-hyperplanes (with k>4) satisfies a strictly weaker condition: the number of 2t-element matroids in the class is dominated by the number of 2t-element excluded minors. However, there are only finitely many excluded minors with ground sets of odd size.

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Dillon Mayhew, Mike Newman, Geoff Whittle. 2019-07-31. Fractal classes of matroids. https://arxiv.org/abs/1907.13343

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