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If $E$ is a finite set and $k \in \mathbb{N}$, then the uniform matroid of rank $k$ is defined as the matroid generated by taking the collection of $k$ element subsets of $E$ as a basis. Is there an analog of this notion when $E$ is not finite?

Currently reading this paper, other references or examples would be great.

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    Browsing the Wikipedia article suggests that there does not seem to be an agreed-upon definition of an infinite matroid. What definition are you using?2012-06-15
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    @Qiaochu: The purpose of the cited paper is to *give* an axiomatic definition of infinitary matroids with duality; it actually gives five equivalent definitions, in terms of independent sets, bases, closure, circuits, and rank. It turns out that cardinality is too crude a measure, so a notion of relative rank is used that reduces to the usual notion in the finite case.2012-06-15

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