Abstract
When we iterate we are faced with the problem of obtaining for the iteration the good properties of the single steps of iteation. Usually the worst possible vice of a forcing notion is that it collapses ℵ 1. The virtue of not collapsing ℵ 1 is not inherited by the iteration from its single components. As we saw, the virtue of the c.c.c. is inherited by the FS iteration from its components. However the c.c.c. is too strong a requirement. We shall look for a weaker requirement which is more naturally connected to the property of not collapsing ℵ l, and which is inherited by iterations.
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© 1982 Springer-Verlag Berlin Heidelberg
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Shelah, S. (1982). Proper Forcing. In: Proper Forcing. Lecture Notes in Mathematics, vol 940. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-21543-2_3
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DOI: https://doi.org/10.1007/978-3-662-21543-2_3
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-11593-9
Online ISBN: 978-3-662-21543-2
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