2024/05/26 by Benhamou, Tom, Poveda, Alejandro
#FOS: Mathematics #Logic (math.LO)
paper · doi:10.48550/arxiv.2405.16704
We develop the non-normal variations of two classical Prikry-type forcings; namely, Magidor and Radin forcings. We generalize the fact that the non-normal Prikry forcing is a projection of the extender-based to a coordinate of the extender to our forcing and the Radin/Magidor-Radin-extender-based forcing from \citeCarmiMagidorRadin,CarmiRadin. Then, we show that both the non-normal variation of Magidor and Radin forcings can add a Cohen generic function to every limit point of cofinality ω of the generic club. Second, we show that this phenomenon is limited to the cases where the forcings are not designed to change the cofinality of a measurable κ to ω1. Specifically, in the above-mentioned circumstances these forcings do not project onto any κ-distributive forcing. We use that to conclude that the extender-based Radin/Magidor-Radin forcing does not add fresh subsets to κ as well. In the second part of the paper we focus on the natural non-normal variation of Gitik's forcing from \cite[\S3]GitikNonStationary. Our main result shows that this poset can be employed to change the cofinality of a measurable cardinal κ to ω1 while introducing a Cohen subset of κ.