{ "id": "1602.01156", "version": "v1", "published": "2016-02-02T23:52:28.000Z", "updated": "2016-02-02T23:52:28.000Z", "title": "Hanf Number for Scott Sentences of Computable Structures", "authors": [ "Sergey Goncharov", "Julia Knight", "Ioannis Souldatos" ], "categories": [ "math.LO" ], "abstract": "The Hanf number for a set $S$ of sentences in $L_{\\omega_1,\\omega}$ (or some other logic) is the least infinite cardinal $\\kappa$ such that for all $\\varphi\\in S$, if $\\varphi$ has models in all infinite cardinalities less than $\\kappa$, then it has models of all infinite cardinalities. S-D. Friedman asked what is the Hanf number for Scott sentences of computable structures. We show that the value is $\\beth_{\\omega_1^{CK}}$.", "revisions": [ { "version": "v1", "updated": "2016-02-02T23:52:28.000Z" } ], "analyses": { "keywords": [ "hanf number", "scott sentences", "computable structures", "infinite cardinalities" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2016arXiv160201156G" } } }