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Reasonable ultrafilters, again

Andrzej Roslanowski·Saharon Shelah
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Abstract

We continue investigations of reasonable ultrafilters on uncountable cardinals defined in math.LO/0407498. We introduce stronger properties of ultrafilters and we show that those properties may be handled in lambda-support iterations of reasonably bounding forcing notions. We use this to show that consistently there are reasonable ultrafilters on an inaccessible cardinal lambda with generating system of size less than 2^lambda . We also show how reasonable ultrafilters can be killed by forcing notions which have enough reasonable completeness to be iterated with lambda-supports (and we show the appropriate preservation theorem).

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Andrzej Roslanowski, Saharon Shelah. 2010-09-20. Reasonable ultrafilters, again. https://arxiv.org/abs/math/0605067

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