{ "id": "2012.09201", "version": "v1", "published": "2020-12-16T19:01:11.000Z", "updated": "2020-12-16T19:01:11.000Z", "title": "Trees and tree-like structures in dense digraphs", "authors": [ "Richard Mycroft", "Tássio Naia" ], "comment": "33 pages, 4 figures", "categories": [ "math.CO" ], "abstract": "We prove that every oriented tree on $n$ vertices with bounded maximum degree appears as a spanning subdigraph of every directed graph on $n$ vertices with minimum semidegree at least $n/2+\\mathrm{o}(n)$. This can be seen as a directed graph analogue of a well-known theorem of Koml\\'os, S\\'ark\\\"ozy and Szemer\\'edi. Our result for trees follows from a more general result, allowing the embedding of arbitrary orientations of a much wider class of spanning \"tree-like\" structures, such as a collection of at most $\\mathrm{o}(n^{1/4})$ vertex-disjoint cycles and subdivisions of graphs $H$ with $|H|< n^{(\\log n)^{-1/2}}$ in which each edge is subdivided at least once.", "revisions": [ { "version": "v1", "updated": "2020-12-16T19:01:11.000Z" } ], "analyses": { "subjects": [ "05C20" ], "keywords": [ "dense digraphs", "tree-like structures", "bounded maximum degree appears", "minimum semidegree", "directed graph analogue" ], "note": { "typesetting": "TeX", "pages": 33, "language": "en", "license": "arXiv", "status": "editable" } } }