# Sh:1008

- Shelah, S. (2013).
*Non-reflection of the bad set for \check I_{\theta}[\lambda] and pcf*. Acta Math. Hungar.,**141**(1-2), 11–35. arXiv: 1206.2048 DOI: 10.1007/s10474-013-0344-6 MR: 3102967 -
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[\bar f],S^{ch}_J[\bar f] for \bar f=\langle f_\alpha: \alpha < \lambda\rangle which is <_J-increasing and cofinal in (\prod\limits_{i<\kappa}\lambda_i,<_J)? (Q3) are there somewhat free black boxes? - Version 2015-05-07_12 (23p) published version (25p)

Bib entry

@article{Sh:1008, author = {Shelah, Saharon}, title = {{Non-reflection of the bad set for $\check I_{\theta}[\lambda]$ and pcf}}, journal = {Acta Math. Hungar.}, fjournal = {Acta Mathematica Hungarica}, volume = {141}, number = {1-2}, year = {2013}, pages = {11--35}, issn = {0236-5294}, mrnumber = {3102967}, mrclass = {03E04 (03E05)}, doi = {10.1007/s10474-013-0344-6}, note = {\href{https://arxiv.org/abs/1206.2048}{arXiv: 1206.2048}}, arxiv_number = {1206.2048} }