DOWNWARD TRANSFERENCE OF MICE AND UNIVERSALITY OF LOCAL CORE MODELS

Abstract

AbstractIf M is a proper class inner model of ZFC and $\omega _2^{\bf{M}} = \omega _2 $, then every sound mouse projecting to ω and not past 0¶ belongs to M. In fact, under the assumption that 0¶ does not belong to M, ${\bf{K}}^{\bf{M}} \parallel \omega _2 $ is universal for all countable mice in V.Similarly, if M is a proper class inner model of ZFC, δ > ω1 is regular, (δ+)M = δ+ and in V there is no proper class inner model with a Woodin cardinal, then ${\bf{K}}^{\bf{M}} \parallel \delta $ is universal for all mice in V of cardinality less than δ.