Conservativity spectra and generalized Ignatiev model

Abstract

We study a generalization of the notion of conservativity spectrum of an arithmetical theory to a language with transfinitely many truth definitions. We establish a correspondence of conservativity spectra and points of a generalized Ignatied model introduced and studied by D. Fernández-Duque and J. Joosten. We also prove the so-called Schmerl formulas for iterated reflection principles of predicative strength.

9 pages