{ "id": "math/0404240", "version": "v1", "published": "2004-04-13T02:03:46.000Z", "updated": "2004-04-13T02:03:46.000Z", "title": "The pair $(\\aleph_n,\\aleph_0)$ may fail $\\aleph_0$--compactness", "authors": [ "Saharon Shelah" ], "categories": [ "math.LO" ], "abstract": "Let P be a distinguished unary predicate and K= {M: M a model of cardinality aleph_n with P^M of cardinality aleph_0}. We prove that consistently for n=4, for some countable first order theory T we have: T has no model in K whereas every finite subset of T has a model in K. We then show how we prove it also for n=2, too.", "revisions": [ { "version": "v1", "updated": "2004-04-13T02:03:46.000Z" } ], "analyses": { "keywords": [ "compactness", "countable first order theory", "finite subset", "cardinality", "distinguished unary predicate" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2004math......4240S" } } }