Tag Archives: reflection principles

A few years ago, in this paper, I introduced the following reflection principle: Definition. $R_2(\theta ,\kappa )$ asserts that for every function $f:E_{<\kappa }^{\theta }\to \kappa$, there exists some $j<\kappa$ for which the following set is nonstationary: $$A_j:=\{\delta \in E_{\kappa }^{\theta }\mid f^{-1}[j]\cap \delta \text{ is nonstationary}\}.$$ I wrote there … Continue reading →