{ "id": "2102.00323", "version": "v1", "published": "2021-01-30T22:04:17.000Z", "updated": "2021-01-30T22:04:17.000Z", "title": "Paths of Length Three are $K_{r+1}$-TurĂ¡n Good", "authors": [ "Kyle Murphy", "JD Nir" ], "comment": "24 pages", "categories": [ "math.CO" ], "abstract": "The generalized Tur\\'an problem $ext(n,T,F)$ is to determine the maximal number of copies of a graph $T$ that can exist in an $F$-free graph on $n$ vertices. Recently, Gerbner and Palmer noted that the solution to the generalized Tur\\'an problem is often the original Tur\\'an graph. They gave the name \"$F$-Tur\\'an-good\" to graphs $T$ for which, for large enough $n$, the solution to the generalized Tur\\'an problem is realized by a Tur\\'an graph. They prove that the path graph on two edges, $P_2$, is $K_{r+1}$-Tur\\'an-good for all $r \\ge 3$, but they conjecture that the same result should hold for all $P_\\ell$. In this paper, using arguments based in flag algebras, we prove that the path on three edges, $P_3$, is also $K_{r+1}$-Tur\\'an-good for all $r \\ge 3$.", "revisions": [ { "version": "v1", "updated": "2021-01-30T22:04:17.000Z" } ], "analyses": { "keywords": [ "generalized turan problem", "turan-good", "original turan graph", "flag algebras", "free graph" ], "note": { "typesetting": "TeX", "pages": 24, "language": "en", "license": "arXiv", "status": "editable" } } }