{"title":"基于图a α-谱半径大小的因子{K1,2,K1,3,K5}的存在性","authors":"Xianglong Zhang, Lihua You","doi":"10.1016/j.dam.2025.06.003","DOIUrl":null,"url":null,"abstract":"<div><div>Let <span><math><mi>G</mi></math></span> be a connected graph of order <span><math><mi>n</mi></math></span>. A <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor of <span><math><mi>G</mi></math></span> is a spanning subgraph of <span><math><mi>G</mi></math></span>, in which each component is isomorphic to a member in <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>. The <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><mi>G</mi></math></span> is denoted by <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>α</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. In this paper, we obtain a lower bound on the size (resp. the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius for <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>[</mo><mn>0</mn><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>]</mo></mrow></mrow></math></span>) of <span><math><mi>G</mi></math></span> to guarantee that <span><math><mi>G</mi></math></span> has a <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor, and show that <span><math><mi>G</mi></math></span> has a <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor if <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>α</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>></mo><mi>τ</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span> is the largest root of <span><math><mrow><msup><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>−</mo><mrow><mo>(</mo><mrow><mo>(</mo><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>+</mo><mi>α</mi><mo>−</mo><mn>3</mn><mo>)</mo></mrow><msup><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><mi>α</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><mi>α</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>−</mo><mn>2</mn><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>x</mi><mo>−</mo><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><mn>3</mn><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>−</mo><mn>4</mn><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mn>5</mn><mi>α</mi><mo>−</mo><mn>3</mn><mo>=</mo><mn>0</mn></mrow></math></span>.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"376 ","pages":"Pages 22-30"},"PeriodicalIF":1.0000,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"The existence of a {K1,2,K1,3,K5}-factor based on the size or the Aα-spectral radius of graphs\",\"authors\":\"Xianglong Zhang, Lihua You\",\"doi\":\"10.1016/j.dam.2025.06.003\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Let <span><math><mi>G</mi></math></span> be a connected graph of order <span><math><mi>n</mi></math></span>. A <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor of <span><math><mi>G</mi></math></span> is a spanning subgraph of <span><math><mi>G</mi></math></span>, in which each component is isomorphic to a member in <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>. The <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius of <span><math><mi>G</mi></math></span> is denoted by <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>α</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. In this paper, we obtain a lower bound on the size (resp. the <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>α</mi></mrow></msub></math></span>-spectral radius for <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>[</mo><mn>0</mn><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo>]</mo></mrow></mrow></math></span>) of <span><math><mi>G</mi></math></span> to guarantee that <span><math><mi>G</mi></math></span> has a <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor, and show that <span><math><mi>G</mi></math></span> has a <span><math><mrow><mo>{</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>3</mn></mrow></msub><mo>,</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>5</mn></mrow></msub><mo>}</mo></mrow></math></span>-factor if <span><math><mrow><msub><mrow><mi>ρ</mi></mrow><mrow><mi>α</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>></mo><mi>τ</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>τ</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span> is the largest root of <span><math><mrow><msup><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>−</mo><mrow><mo>(</mo><mrow><mo>(</mo><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>+</mo><mi>α</mi><mo>−</mo><mn>3</mn><mo>)</mo></mrow><msup><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><mi>α</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><mi>α</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>−</mo><mn>2</mn><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>x</mi><mo>−</mo><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mrow><mo>(</mo><mn>3</mn><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>−</mo><mi>α</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mi>n</mi><mo>−</mo><mn>4</mn><msup><mrow><mi>α</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><mn>5</mn><mi>α</mi><mo>−</mo><mn>3</mn><mo>=</mo><mn>0</mn></mrow></math></span>.</div></div>\",\"PeriodicalId\":50573,\"journal\":{\"name\":\"Discrete Applied Mathematics\",\"volume\":\"376 \",\"pages\":\"Pages 22-30\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2025-06-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete Applied Mathematics\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0166218X2500318X\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS, APPLIED\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete Applied Mathematics","FirstCategoryId":"100","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0166218X2500318X","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
The existence of a {K1,2,K1,3,K5}-factor based on the size or the Aα-spectral radius of graphs
Let be a connected graph of order . A -factor of is a spanning subgraph of , in which each component is isomorphic to a member in . The -spectral radius of is denoted by . In this paper, we obtain a lower bound on the size (resp. the -spectral radius for ) of to guarantee that has a -factor, and show that has a -factor if , where is the largest root of .
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