Meagreness of the Ramsey cone topology

ID: meagreness-of-the-ramsey-cone-topology

The whole space of infinite subsets of the natural numbers is a meagre set in the Ramsey cone topology. For , the closure is , which has empty interior: every infinite ground set can be thinned to omit . Thus all are nowhere dense, while their countable union is the whole space. In contrast, the whole space is not meagre in either the Ellentuck topology or the ordinary topology on infinite subsets.

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