{ "id": "1805.06767", "version": "v1", "published": "2018-05-17T13:43:58.000Z", "updated": "2018-05-17T13:43:58.000Z", "title": "Model theory of Steiner triple systems", "authors": [ "Silvia Barbina", "Enrique Casanovas" ], "categories": [ "math.LO" ], "abstract": "A Steiner triple system is a set $S$ together with a collection $\\mathcal{B}$ of subsets of $S$ of size 3 such that any two elements of $S$ belong to exactly one element of $\\mathcal{B}$. It is well known that the class of finite Steiner triple systems has a Fra\\\"{\\i}ss\\'e limit $M_{\\mathrm{F}}$. Here we show that the theory $T^\\ast_\\mathrm{Sq}$ of $M_{\\mathrm{F}}$ is the model completion of the theory of Steiner triple systems. We also prove that $T^\\ast_\\mathrm{Sq}$ has quantifier elimination, it is not small and has $\\mathrm{TP}_2$ and $\\mathrm{NSOP}_1$.", "revisions": [ { "version": "v1", "updated": "2018-05-17T13:43:58.000Z" } ], "analyses": { "keywords": [ "model theory", "finite steiner triple systems", "quantifier elimination", "model completion", "collection" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }