{ "id": "1311.4053", "version": "v2", "published": "2013-11-16T12:56:41.000Z", "updated": "2019-09-17T15:06:53.000Z", "title": "A dichotomy for $D$-rank 1 types in simple theories", "authors": [ "Ziv Shami" ], "comment": "One corollary added at the end of the article, more details added in proofs and minor correction made in the proof of Corollary 3.21", "categories": [ "math.LO" ], "abstract": "We prove a dichotomy for $D$-rank 1 types in simple theories that generalizes Buechler's dichotomy for $D$-rank 1 minimal types: every such type is either 1-based or its algebraic closure, by a single formula, almost contains a non-algebraic formula that belongs to a non-forking extension of the type. In addition we prove that a densely-1 based type of $D$-rank 1 is 1-based. We also observe that for a hypersimple unidimensional theory the existence of a non-algebraic stable type implies stability (and thus superstability).", "revisions": [ { "version": "v1", "updated": "2013-11-16T12:56:41.000Z", "comment": null, "journal": null, "doi": null }, { "version": "v2", "updated": "2019-09-17T15:06:53.000Z" } ], "analyses": { "keywords": [ "simple theories", "non-algebraic stable type implies stability", "hypersimple unidimensional theory", "generalizes buechlers dichotomy", "algebraic closure" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1311.4053S" } } }