{ "id": "2311.18753", "version": "v1", "published": "2023-11-30T17:54:13.000Z", "updated": "2023-11-30T17:54:13.000Z", "title": "A note on extremal constructions for the Erdős--Rademacher problem", "authors": [ "Xizhi Liu", "Oleg Pikhurko" ], "comment": "short note, 13 pages, comments are welcome", "categories": [ "math.CO" ], "abstract": "For given positive integers $r\\ge 3$, $n$ and $e\\le \\binom{n}{2}$, the famous Erd\\H{o}s--Rademacher problem asks for the minimum number of $r$-cliques in a graph with $n$ vertices and $e$ edges. A conjecture of Lov\\'{a}sz and Simonovits from the 1970s states that, for every $r\\ge 3$, if $n$ is sufficiently large then, for every $e\\le \\binom{n}{2}$, at least one extremal graph can be obtained from a complete partite graph by adding a triangle-free graph into one part. In this note, we explicitly write the minimum number of $r$-cliques predicted by the above conjecture. Also, we describe what we believe to be the set of extremal graphs for any $r\\ge 4$ and all large $n$, amending the previous conjecture of Pikhurko and Razborov.", "revisions": [ { "version": "v1", "updated": "2023-11-30T17:54:13.000Z" } ], "analyses": { "subjects": [ "05C35" ], "keywords": [ "extremal constructions", "erdős-rademacher problem", "minimum number", "extremal graph", "conjecture" ], "note": { "typesetting": "TeX", "pages": 13, "language": "en", "license": "arXiv", "status": "editable" } } }