{ "id": "1910.11230", "version": "v1", "published": "2019-10-24T15:36:20.000Z", "updated": "2019-10-24T15:36:20.000Z", "title": "Counting siblings in universal theories", "authors": [ "Samuel Braunfeld", "Michael C. Laskowski" ], "comment": "25 pages", "categories": [ "math.LO" ], "abstract": "We show that if a countable structure $M$ in a finite relational language is not cellular, then there is an age-preserving $N \\supseteq M$ such that $2^{\\aleph_0}$ many structures are bi-embeddable with $N$. The proof proceeds by a case division based on mutual algebraicity.", "revisions": [ { "version": "v1", "updated": "2019-10-24T15:36:20.000Z" } ], "analyses": { "subjects": [ "03C15" ], "keywords": [ "universal theories", "counting siblings", "finite relational language", "case division", "proof proceeds" ], "note": { "typesetting": "TeX", "pages": 25, "language": "en", "license": "arXiv", "status": "editable" } } }