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arXiv · 1206.2048

Non-reflection of the bad set for {check I}_theta[lambda] and pcf

Saharon Shelah
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Abstract

We reconsider here the following related pcf questions and make some advances: (Q1) concerning the ideal {check I}_kappa [lambda] how much reflection do we have for the bad set S^{bd}_{lambda, kappa} subseteq {delta < lambda : cf(delta)= kappa} assuming it is well defined? (Q2) for an ideal J on kappa how large are S^{bd}_J[f],S^{ch}_J[f] for f=< f_alpha : alpha which is <_J-increasing and cofinal in (prod limits_{i< kappa} lambda_i,<_J) ? (Q3) are there somewhat free black boxes?

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Saharon Shelah. 2012-06-23. Non-reflection of the bad set for {check I}_theta[lambda] and pcf. https://arxiv.org/abs/1206.2048

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