{ "id": "1709.03901", "version": "v1", "published": "2017-09-12T15:12:22.000Z", "updated": "2017-09-12T15:12:22.000Z", "title": "Local resilience of an almost spanning $k$-cycle in random graphs", "authors": [ "Nemanja Škorić", "Angelika Steger", "Miloš Trujić" ], "categories": [ "math.CO" ], "abstract": "The famous P\\'{o}sa-Seymour conjecture states that for any $k \\geq 2$, a graph $G = (V, E)$ with minimum degree $kn/(k + 1)$ contains the $k$-th power of a Hamilton cycle. The conjecture was confirmed a couple of decades later by Koml\\'{o}s, S\\'{a}rk\\\"{o}zy, and Szemer\\'{e}di. We extend this result to a sparse setting. We show that for all $k \\geq 2$ and $\\varepsilon, \\alpha > 0$, if $p \\geq C(\\log{N}/N)^{1/k}$ then any subgraph of a random graph $G_{N, p}$ with minimum degree at least $(k/(k + 1) + \\alpha)Np$, w.h.p.\\ contains the $k$-th power of a cycle on at least $(1 - \\varepsilon)N$ vertices, improving upon the recent results of Noever and Steger for $k = 2$, as well as Allen, B\\\"{o}ttcher, Ehrenm\\\"{u}ller, and Taraz for $k \\geq 3$. Our result is almost best possible in three ways: $(1)$ for $p \\ll N^{-1/k}$ the random graph $G_{N, p}$ almost surely does not contain the $k$-th power of any long cycle; $(2)$ there exist subgraphs of $G_{N, p}$ with minimum degree $(k/(k + 1) + \\alpha)Np$ and $\\Omega(p^{-2})$ vertices not belonging to any triangles; $(3)$ there exist subgraphs of $G_{N, p}$ with minimum degree $(k/(k + 1) - \\alpha)Np$ which do not contain the $k$-th power of a cycle on $(1 - \\varepsilon)N$ vertices.", "revisions": [ { "version": "v1", "updated": "2017-09-12T15:12:22.000Z" } ], "analyses": { "keywords": [ "random graph", "minimum degree", "th power", "local resilience", "conjecture states" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }