Editing Extendible cardinal (section)

In [[mathematics]], '''extendible cardinals''' are [[large cardinal]]s introduced by {{harvtxt|Reinhardt|1974}}, who was partly motivated by [[reflection principle]]s.  Intuitively, such a cardinal represents a point beyond which initial pieces of the [[Von Neumann universe|universe of sets]] start to look similar, in the sense that each is [[elementary embedding|elementarily embeddable]] into a later one.