{ "id": "math/9212202", "version": "v1", "published": "1992-12-02T00:00:00.000Z", "updated": "1992-12-02T00:00:00.000Z", "title": "A large Pi-1-2 set absolute for set forcing", "authors": [ "Sy D. Friedman" ], "categories": [ "math.LO" ], "abstract": "Let k be a definable L-cardinal. Then there is a set of reals X, class-generic over L, such that L(X) and L have the same cardinals, X has size k in L(X) and some pi-1-2 formula defines X in all set-generic extensions of L(X). Two corollaries, both assuming the consistency of an inaccessible: It is consistent for the Perfect Set Property to hold for boldface sigma-1-2 sets, yet fail for some lightface pi-1-2 set. It is consistent that the Perfect Set Property holds for boldface sigma-1-2 sets yet some lightface pi-1-2 wellordering of some set of reals has length aleph-1000.", "revisions": [ { "version": "v1", "updated": "1992-12-02T00:00:00.000Z" } ], "analyses": { "keywords": [ "set absolute", "set forcing", "perfect set property holds", "formula defines", "set-generic extensions" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "1992math.....12202F" } } }