# On the number of matroids compared to the number of sparse paving matroids

J.G. Pol, van der, R.A. Pendavingh

## Abstract

It has been conjectured that sparse paving matroids will eventually predominate in any asymptotic enumeration of matroids, i.e. that $\lim_{n\rightarrow\infty} s_n/m_n = 1$, where $m_n$ denotes the number of matroids on $n$ elements, and $s_n$ the number of sparse paving matroids. In this paper, we show that $$\lim_{n\rightarrow \infty}\frac{\log s_n}{\log m_n}=1.$$ We prove this by arguing that each matroid on $n$ elements has a faithful description consisting of a stable set of a Johnson graph together with a (by comparison) vanishing amount of other information, and using that stable sets in these Johnson graphs correspond 1-1 to sparse paving matroids on $n$ elements.
Original language English s.n. 12 Published - 2014

### Publication series

Name arXiv.org 1411.0935 [math.CO]

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