{ "id": "2106.03261", "version": "v1", "published": "2021-06-06T22:08:59.000Z", "updated": "2021-06-06T22:08:59.000Z", "title": "Which graphs can be counted in $C_4$-free graphs?", "authors": [ "David Conlon", "Jacob Fox", "Benny Sudakov", "Yufei Zhao" ], "comment": "13 pages", "categories": [ "math.CO" ], "abstract": "For which graphs $F$ is there a sparse $F$-counting lemma in $C_4$-free graphs? We are interested in identifying graphs $F$ with the property that, roughly speaking, if $G$ is an $n$-vertex $C_4$-free graph with on the order of $n^{3/2}$ edges, then the density of $F$ in $G$, after a suitable normalization, is approximately at least the density of $F$ in an $\\epsilon$-regular approximation of $G$. In recent work, motivated by applications in extremal and additive combinatorics, we showed that $C_5$ has this property. Here we construct a family of graphs with the property.", "revisions": [ { "version": "v1", "updated": "2021-06-06T22:08:59.000Z" } ], "analyses": { "keywords": [ "free graph", "regular approximation", "suitable normalization", "identifying graphs", "counting lemma" ], "note": { "typesetting": "TeX", "pages": 13, "language": "en", "license": "arXiv", "status": "editable" } } }