{"title":"关于有向图连通性的说明","authors":"Stelios Stylianou","doi":"arxiv-2409.12137","DOIUrl":null,"url":null,"abstract":"We say a directed graph $G$ on $n$ vertices is irredundant if the removal of\nany edge reduces the number of ordered pairs of distinct vertices $(u,v)$ such\nthat there exists a directed path from $u$ to $v$. We determine the maximum\npossible number of edges such a graph can have, for every $n \\in \\mathbb{N}$.\nWe also characterize the cases of equality. This resolves, in a strong form, a\nquestion of Crane and Russell.","PeriodicalId":501407,"journal":{"name":"arXiv - MATH - Combinatorics","volume":"50 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A note on connectivity in directed graphs\",\"authors\":\"Stelios Stylianou\",\"doi\":\"arxiv-2409.12137\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We say a directed graph $G$ on $n$ vertices is irredundant if the removal of\\nany edge reduces the number of ordered pairs of distinct vertices $(u,v)$ such\\nthat there exists a directed path from $u$ to $v$. We determine the maximum\\npossible number of edges such a graph can have, for every $n \\\\in \\\\mathbb{N}$.\\nWe also characterize the cases of equality. This resolves, in a strong form, a\\nquestion of Crane and Russell.\",\"PeriodicalId\":501407,\"journal\":{\"name\":\"arXiv - MATH - Combinatorics\",\"volume\":\"50 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - MATH - Combinatorics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2409.12137\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - MATH - Combinatorics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.12137","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
We say a directed graph $G$ on $n$ vertices is irredundant if the removal of
any edge reduces the number of ordered pairs of distinct vertices $(u,v)$ such
that there exists a directed path from $u$ to $v$. We determine the maximum
possible number of edges such a graph can have, for every $n \in \mathbb{N}$.
We also characterize the cases of equality. This resolves, in a strong form, a
question of Crane and Russell.