{ "id": "2004.06097", "version": "v1", "published": "2020-04-13T17:56:41.000Z", "updated": "2020-04-13T17:56:41.000Z", "title": "Saturation problems in the Ramsey theory of graphs, posets and point sets", "authors": [ "Gábor Damásdi", "Balázs Keszegh", "David Malec", "Casey Tompkins", "Zhiyu Wang", "Oscar Zamora" ], "categories": [ "math.CO" ], "abstract": "In 1964, Erd\\H{o}s, Hajnal and Moon introduced a saturation version of Tur\\'an's classical theorem in extremal graph theory. In particular, they determined the minimum number of edges in a $K_r$-free, $n$-vertex graph with the property that the addition of any further edge yields a copy of $K_r$. We consider analogues of this problem in other settings. We prove a saturation version of the Erd\\H{o}s-Szekeres theorem about monotone subsequences and saturation versions of some Ramsey-type theorems on graphs and Dilworth-type theorems on posets. We also consider semisaturation problems, wherein we allow the family to have the forbidden configuration, but insist that any addition to the family yields a new copy of the forbidden configuration. In this setting, we prove a semisaturation version of the Erd\\H{o}s-Szekeres theorem on convex $k$-gons, as well as multiple semisaturation theorems for sequences and posets.", "revisions": [ { "version": "v1", "updated": "2020-04-13T17:56:41.000Z" } ], "analyses": { "keywords": [ "ramsey theory", "saturation problems", "point sets", "saturation version", "forbidden configuration" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }