{ "id": "2108.12669", "version": "v1", "published": "2021-08-28T16:05:59.000Z", "updated": "2021-08-28T16:05:59.000Z", "title": "Triangle-free planar graphs with at most $64^{n^{0.731}}$ 3-colorings", "authors": [ "Zdeněk Dvořák", "Luke Postle" ], "comment": "4 pages, 1 figure", "categories": [ "math.CO" ], "abstract": "Thomassen conjectured that triangle-free planar graphs have exponentially many 3-colorings. Recently, he disproved his conjecture by providing examples of such graphs with $n$ vertices and at most $2^{15n/\\log_2 n}$ 3-colorings. We improve his construction, giving examples of such graphs with at most $64^{n^{log_{9/2} 3}}<64^{n^{0.731}}$ 3-colorings. We conjecture this exponent is optimal.", "revisions": [ { "version": "v1", "updated": "2021-08-28T16:05:59.000Z" } ], "analyses": { "subjects": [ "05C15" ], "keywords": [ "triangle-free planar graphs", "conjecture", "construction" ], "note": { "typesetting": "TeX", "pages": 4, "language": "en", "license": "arXiv", "status": "editable" } } }