# Sh:805

- Gitik, M., Schindler, R.-D., & Shelah, S. (2006).
*PCF theory and Woodin cardinals*. In Logic Colloquium ’02, Vol. 27, Assoc. Symbol. Logic, La Jolla, CA, pp. 172–205. arXiv: math/0211433 MR: 2258707 -
Abstract:

We prove the following two results. Theorem A: Let \alpha be a limit ordinal. Suppose that 2^{|\alpha|}<\aleph_\alpha and 2^{|\alpha|^+}<\aleph_{| \alpha|^+}, whereas \aleph_\alpha^{|\alpha|}>\aleph_{| \alpha|^+}. Then for all n<\omega and for all bounded X\subset \aleph_{|\alpha|^+}, M_n^\#(X) exists.Theorem B: Let \kappa be a singular cardinal of uncountable cofinality. If \{\alpha<\kappa\ | \ 2^\alpha=\alpha^+\} is stationary as well as co-stationary then for all n<\omega and for all bounded X\subset\kappa, M_n^\#(X) exists.

Theorem A answers a question of Gitik and Mitchell, and Theorem B yields a lower bound for an assertion discussed in Gitik, M.,

*Introduction to Prikry type forcing notions*, in: Handbook of set theory, Foreman, Kanamori, Magidor (see Problem 4 there).The proofs of these theorems combine pcf theory with core model theory. Along the way we establish some ZFC results in cardinal arithmetic, motivated by Silver’s theorem and we obtain results of core model theory, motivated by the task of building a “stable core model.” Both sets of results are of independent interest.

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@incollection{Sh:805, author = {Gitik, Moti and Schindler, Ralf-Dieter and Shelah, Saharon}, title = {{PCF theory and Woodin cardinals}}, booktitle = {{Logic Colloquium '02}}, series = {Lect. Notes Log.}, volume = {27}, year = {2006}, pages = {172--205}, mrclass = {03E04 (03E35 03E45 03E55)}, mrnumber = {2258707}, publisher = {Assoc. Symbol. Logic, La Jolla, CA}, note = {\href{https://arxiv.org/abs/math/0211433}{arXiv: math/0211433}}, arxiv_number = {math/0211433} }