NUI Galway Mathematics
Preprint IRL-GLWY-2006-002 (PDF)

℘(ℝ), ordered by homeomorphic embeddability, does not represent all posets of cardinality 2c.

Robin W. Knight and Aisling McCluskey

Abstract

We prove it to be consistent that there is a poset of cardinality 2c which is not realizable in ℘(ℝ), ordered by homeomorphic embeddability. This addresses and answers resolutely (and in the negative) the open question of whether there is a ZFC theorem that all posets of cardinality 2c can be represented by subspaces of the real line ordered by homeomorphic embeddability. This question arises from the pioneering work of Banach, Kuratowski and Sierpinski in the area and this result complements the recent work of [9], thus providing a proof of independence.

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