Decreasing chains without lower bounds in Rudin-Frol\'ik order for regulars

Abstract

The aim of this paper is to prove that for there exist a chain in the Rudin-Frol\'ik order of $\beta\kappa\setminus \kappa$ of length $\mu$ with $\kappa \leqslant \mu \leqslant 2^\kappa$ for regular $\kappa> \omega$ without a lower bound.