Abstract
We show that strongly compact cardinals and MM are sensitive to $\lambda$-closed forcings for arbitrarily large $\lambda$. This is done by adding ‘regressive' $\lambda$-Kurepa trees in either case. We argue that the destruction of regressive Kurepa trees requires a non-standard application of MM. As a corollary, we find a consistent example of an $\omega_2$-closed poset that is not forcing equivalent to any $\omega_2$-directed-closed poset.
Citation
Bernhard König. Yasuo Yoshinobu. "Kurepa trees and Namba forcing." J. Symbolic Logic 77 (4) 1281 - 1290, December 2012. https://doi.org/10.2178/jsl.7704130
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