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Kurepa-trees and Namba forcing
by
Bernhard Koenig
Boise State University
Coauthors: Yasuo Yoshinobu
We show that MM is sensitive to l-closed forcings for arbitrarily large l. This is interesting in the sense that all other forcing axioms (e.g. PFA, PFA+) are indestructible by w2-closed forcings. We achieve this result by adding certain types of 'regressive' Kurepa-trees. These trees can be destroyed with a forcing axiom but Namba forcing is required here.
Similar destructibility results are presented for compact cardinals.
Date received: February 19, 2005
Copyright © 2005 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # capk-04.