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A universal continuum of weight
Authors:Alan Dow  Klaas Pieter Hart
Institution:Department of Mathematics and Statistics, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3 ; Faculty of Technical Mathematics and Informatics, TU Delft, Postbus 5031, 2600 GA Delft, The Netherlands
Abstract:

We prove that every continuum of weight $\aleph_1$ is a continuous image of the Cech-Stone-remainder $R^*$ of the real line. It follows that under  $\mathsf{CH}$ the remainder of the half line $0,\infty)$ is universal among the continua of weight  $\mathfrak{c}$-- universal in the `mapping onto' sense.

We complement this result by showing that 1) under  $\mathsf{MA}$ every continuum of weight less than  $\mathfrak{c}$ is a continuous image of $R^*$, 2) in the Cohen model the long segment of length  $\omega_2+1$ is not a continuous image of $R^*$, and 3)  $\mathsf{PFA}$ implies that $I_u$ is not a continuous image of $R^*$, whenever $u$ is a $\mathfrak{c}$-saturated ultrafilter.

We also show that a universal continuum can be gotten from a $\mathfrak{c}$-saturated ultrafilter on $\omega$, and that it is consistent that there is no universal continuum of weight  $\mathfrak{c}$.

Keywords:Parovi\v{c}enko's theorem  universal continuum  remainder of $[0  \infty)$  $\aleph_1$-saturated model  elementary equivalence  Continuum Hypothesis  Cohen reals  long segment  Martin's Axiom  Proper Forcing Axiom  saturated ultrafilter
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