{ "id": "1706.03276", "version": "v1", "published": "2017-06-10T20:14:59.000Z", "updated": "2017-06-10T20:14:59.000Z", "title": "Interval orders, semiorders and ordered groups", "authors": [ "Maurice Pouzet", "Imed Zaguia" ], "categories": [ "math.CO" ], "abstract": "We prove that the order of an ordered group is an interval order if and only if it is a semiorder. Next, we prove that every semiorder is isomorphic to a collection $\\mathcal J$ of intervals of some totally ordered abelian group, these intervals being of the form $[x, x+ \\alpha[$ for some positive $\\alpha$. We describe ordered groups such that the ordering is a semiorder and we introduce threshold groups generalizing totally ordered groups. We show that the free group on finitely many generators and the Thompson group $\\mathbb F$ can be equipped with a semiorder which is not a weak order. On an other hand, a group introduced by Clifford cannot.", "revisions": [ { "version": "v1", "updated": "2017-06-10T20:14:59.000Z" } ], "analyses": { "keywords": [ "interval order", "free group", "totally ordered abelian group", "weak order", "groups generalizing totally ordered groups" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }