Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6424850 | Annals of Pure and Applied Logic | 2011 | 40 Pages |
â¢Â We define a notion of order of indiscernibility type of a structure by analogy with Mitchell order on measures; we use this to define a hierarchy of strong axioms of infinity defined through normal filters, the α-weakly ErdÅs hierarchy. The filters in this hierarchy can be seen to be generated by sets of ordinals where these indiscernibility orders on structures dominate the canonical functions.â¢Â The limit axiom of this is that of greatly ErdÅs and we use it to calibrate some strengthenings of the Chang property, one of which, CC+, is equiconsistent with a Ramsey cardinal, and implies that Ï3=(Ï2+)K where K is the core model built with non-overlapping extenders - if it is rigid, and others which are a little weaker. As one corollary we have: TheoremIf CC+â§Â¬â¡Ï2then there is an inner model with a strong cardinal. â¢Â We define an α-Jónsson hierarchy to parallel the α-Ramsey hierarchy, and show that κ being α-Jónsson implies that it is α-Ramsey in the core model.