{ "id": "1306.4940", "version": "v5", "published": "2013-06-20T17:34:38.000Z", "updated": "2014-06-18T20:35:25.000Z", "title": "Weak Rudin-Keisler reductions on projective ideals", "authors": [ "Konstantinos A. Beros" ], "comment": "11 pages", "categories": [ "math.LO", "math.GR" ], "abstract": "We consider a slightly modified form of the standard Rudin-Keisler order on ideals and demonstrate the existence of complete (with respect to this order) ideals in various projective classes. Using our methods, we obtain a simple proof of Hjorth's theorem on the existence of a complete $\\mathbf \\Pi^1_1$ equivalence relation. Our proof of Hjorth's theorem enables us (under PD) to generalize his result to the classes of $\\mathbf \\Pi^1_{2n+1}$ equivalence relations.", "revisions": [ { "version": "v5", "updated": "2014-06-18T20:35:25.000Z" } ], "analyses": { "subjects": [ "03E15", "03E60", "03E05", "28A05" ], "keywords": [ "weak rudin-keisler reductions", "projective ideals", "equivalence relation", "hjorths theorem enables", "standard rudin-keisler order" ], "note": { "typesetting": "TeX", "pages": 11, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1306.4940B" } } }