{"title":"Minimum bull-saturated graphs","authors":"Xinying Hua, Yuejian Peng","doi":"10.1016/j.disc.2025.114674","DOIUrl":null,"url":null,"abstract":"<div><div>For a given graph family <span><math><mi>F</mi></math></span>, a graph <em>G</em> is said to be <span><math><mi>F</mi></math></span><em>-saturated</em> if <em>G</em> contains no member of <span><math><mi>F</mi></math></span> as a subgraph but the addition of any edge to <em>G</em> produces a member of <span><math><mi>F</mi></math></span>. If <span><math><mi>F</mi><mo>=</mo><mo>{</mo><mi>F</mi><mo>}</mo></math></span>, then <em>G</em> is said to be an <em>F-saturated graph</em>. The <em>saturation number</em> of <em>F</em>, denoted by <span><math><mrow><mi>sat</mi></mrow><mo>(</mo><mi>n</mi><mo>,</mo><mspace></mspace><mi>F</mi><mo>)</mo></math></span>, is the minimum number of edges in an <em>F</em>-saturated graph with <em>n</em> vertices. A <em>bull</em> is the graph obtained by attaching two leaves to two vertices of a triangle. In this paper, we determine the saturation number of a bull and characterize corresponding minimum bull-saturated graphs.</div></div>","PeriodicalId":50572,"journal":{"name":"Discrete Mathematics","volume":"349 1","pages":"Article 114674"},"PeriodicalIF":0.7000,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012365X25002821","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
For a given graph family , a graph G is said to be -saturated if G contains no member of as a subgraph but the addition of any edge to G produces a member of . If , then G is said to be an F-saturated graph. The saturation number of F, denoted by , is the minimum number of edges in an F-saturated graph with n vertices. A bull is the graph obtained by attaching two leaves to two vertices of a triangle. In this paper, we determine the saturation number of a bull and characterize corresponding minimum bull-saturated graphs.
期刊介绍:
Discrete Mathematics provides a common forum for significant research in many areas of discrete mathematics and combinatorics. Among the fields covered by Discrete Mathematics are graph and hypergraph theory, enumeration, coding theory, block designs, the combinatorics of partially ordered sets, extremal set theory, matroid theory, algebraic combinatorics, discrete geometry, matrices, and discrete probability theory.
Items in the journal include research articles (Contributions or Notes, depending on length) and survey/expository articles (Perspectives). Efforts are made to process the submission of Notes (short articles) quickly. The Perspectives section features expository articles accessible to a broad audience that cast new light or present unifying points of view on well-known or insufficiently-known topics.