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{"title":"最小非色λ可选图","authors":"Jialu Zhu, Xuding Zhu","doi":"10.1002/jgt.23267","DOIUrl":null,"url":null,"abstract":"<div>\n \n <p>For a multiset <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n \n <mo>=</mo>\n \n <mrow>\n <mo>{</mo>\n \n <mrow>\n <msub>\n <mi>k</mi>\n \n <mn>1</mn>\n </msub>\n \n <mo>,</mo>\n \n <msub>\n <mi>k</mi>\n \n <mn>2</mn>\n </msub>\n \n <mo>,</mo>\n \n <mo>…</mo>\n \n <mo>,</mo>\n \n <msub>\n <mi>k</mi>\n \n <mi>q</mi>\n </msub>\n </mrow>\n \n <mo>}</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> of positive integers, let <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>k</mi>\n \n <mi>λ</mi>\n </msub>\n \n <mo>=</mo>\n \n <msubsup>\n <mo>∑</mo>\n \n <mrow>\n <mi>i</mi>\n \n <mo>=</mo>\n \n <mn>1</mn>\n </mrow>\n \n <mi>q</mi>\n </msubsup>\n \n <msub>\n <mi>k</mi>\n \n <mi>i</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>. A <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-list assignment of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> is a list assignment <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>L</mi>\n </mrow>\n </mrow>\n </semantics></math> of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> such that the colour set <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mo>⋃</mo>\n \n <mrow>\n <mi>v</mi>\n \n <mo>∈</mo>\n \n <mi>V</mi>\n \n <mrow>\n <mo>(</mo>\n \n <mi>G</mi>\n \n <mo>)</mo>\n </mrow>\n </mrow>\n </msub>\n \n <mi>L</mi>\n \n <mrow>\n <mo>(</mo>\n \n <mi>v</mi>\n \n <mo>)</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> can be partitioned into the disjoint union <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>C</mi>\n \n <mn>1</mn>\n </msub>\n \n <mo>∪</mo>\n \n <msub>\n <mi>C</mi>\n \n <mn>2</mn>\n </msub>\n \n <mo>∪</mo>\n \n <mo>⋯</mo>\n \n <mo>∪</mo>\n \n <msub>\n <mi>C</mi>\n \n <mi>q</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math> of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>q</mi>\n </mrow>\n </mrow>\n </semantics></math> sets so that for each <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>i</mi>\n </mrow>\n </mrow>\n </semantics></math> and each vertex <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>v</mi>\n </mrow>\n </mrow>\n </semantics></math> of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math>, <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mo>∣</mo>\n \n <mi>L</mi>\n \n <mrow>\n <mo>(</mo>\n \n <mi>v</mi>\n \n <mo>)</mo>\n </mrow>\n \n <mo>∩</mo>\n \n <msub>\n <mi>C</mi>\n \n <mi>i</mi>\n </msub>\n \n <mo>∣</mo>\n \n <mo>=</mo>\n \n <msub>\n <mi>k</mi>\n \n <mi>i</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>. We say <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> is <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosable if <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> is <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>L</mi>\n </mrow>\n </mrow>\n </semantics></math>-colourable for any <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-list assignment <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>L</mi>\n </mrow>\n </mrow>\n </semantics></math> of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math>. The concept of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosability puts <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math>-colourability and <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosability in a same framework: If <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n \n <mo>=</mo>\n \n <mrow>\n <mo>{</mo>\n \n <mi>k</mi>\n \n <mo>}</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math>, then <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosability is equivalent to <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosability; if <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math> consists of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math> copies of 1, then <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosability is equivalent to <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>k</mi>\n </mrow>\n </mrow>\n </semantics></math>-colourability. If <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> is <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosable, then <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>G</mi>\n </mrow>\n </mrow>\n </semantics></math> is <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>k</mi>\n \n <mi>λ</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>-colourable. On the other hand, there are <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>k</mi>\n \n <mi>λ</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>-colourable graphs that are not <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosable, provided that <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math> contains an integer larger than 1. Let <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>ϕ</mi>\n \n <mrow>\n <mo>(</mo>\n \n <mi>λ</mi>\n \n <mo>)</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> be the minimum number of vertices in a <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <msub>\n <mi>k</mi>\n \n <mi>λ</mi>\n </msub>\n </mrow>\n </mrow>\n </semantics></math>-colourable non-<span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>-choosable graph. This paper determines the value of <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>ϕ</mi>\n \n <mrow>\n <mo>(</mo>\n \n <mi>λ</mi>\n \n <mo>)</mo>\n </mrow>\n </mrow>\n </mrow>\n </semantics></math> for all <span></span><math>\n <semantics>\n <mrow>\n \n <mrow>\n <mi>λ</mi>\n </mrow>\n </mrow>\n </semantics></math>.</p>\n </div>","PeriodicalId":16014,"journal":{"name":"Journal of Graph Theory","volume":"110 3","pages":"283-289"},"PeriodicalIF":1.0000,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Minimum Non-Chromatic-\\n \\n \\n \\n λ\\n \\n \\n -Choosable Graphs\",\"authors\":\"Jialu Zhu, Xuding Zhu\",\"doi\":\"10.1002/jgt.23267\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n <p>For a multiset <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n \\n <mo>=</mo>\\n \\n <mrow>\\n <mo>{</mo>\\n \\n <mrow>\\n <msub>\\n <mi>k</mi>\\n \\n <mn>1</mn>\\n </msub>\\n \\n <mo>,</mo>\\n \\n <msub>\\n <mi>k</mi>\\n \\n <mn>2</mn>\\n </msub>\\n \\n <mo>,</mo>\\n \\n <mo>…</mo>\\n \\n <mo>,</mo>\\n \\n <msub>\\n <mi>k</mi>\\n \\n <mi>q</mi>\\n </msub>\\n </mrow>\\n \\n <mo>}</mo>\\n </mrow>\\n </mrow>\\n </mrow>\\n </semantics></math> of positive integers, let <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mi>k</mi>\\n \\n <mi>λ</mi>\\n </msub>\\n \\n <mo>=</mo>\\n \\n <msubsup>\\n <mo>∑</mo>\\n \\n <mrow>\\n <mi>i</mi>\\n \\n <mo>=</mo>\\n \\n <mn>1</mn>\\n </mrow>\\n \\n <mi>q</mi>\\n </msubsup>\\n \\n <msub>\\n <mi>k</mi>\\n \\n <mi>i</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math>. A <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-list assignment of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> is a list assignment <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>L</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> such that the colour set <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mo>⋃</mo>\\n \\n <mrow>\\n <mi>v</mi>\\n \\n <mo>∈</mo>\\n \\n <mi>V</mi>\\n \\n <mrow>\\n <mo>(</mo>\\n \\n <mi>G</mi>\\n \\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n </msub>\\n \\n <mi>L</mi>\\n \\n <mrow>\\n <mo>(</mo>\\n \\n <mi>v</mi>\\n \\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n </mrow>\\n </semantics></math> can be partitioned into the disjoint union <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mi>C</mi>\\n \\n <mn>1</mn>\\n </msub>\\n \\n <mo>∪</mo>\\n \\n <msub>\\n <mi>C</mi>\\n \\n <mn>2</mn>\\n </msub>\\n \\n <mo>∪</mo>\\n \\n <mo>⋯</mo>\\n \\n <mo>∪</mo>\\n \\n <msub>\\n <mi>C</mi>\\n \\n <mi>q</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math> of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>q</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> sets so that for each <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>i</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> and each vertex <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>v</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>, <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mo>∣</mo>\\n \\n <mi>L</mi>\\n \\n <mrow>\\n <mo>(</mo>\\n \\n <mi>v</mi>\\n \\n <mo>)</mo>\\n </mrow>\\n \\n <mo>∩</mo>\\n \\n <msub>\\n <mi>C</mi>\\n \\n <mi>i</mi>\\n </msub>\\n \\n <mo>∣</mo>\\n \\n <mo>=</mo>\\n \\n <msub>\\n <mi>k</mi>\\n \\n <mi>i</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math>. We say <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> is <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosable if <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> is <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>L</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourable for any <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-list assignment <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>L</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>. The concept of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosability puts <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>k</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourability and <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>k</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosability in a same framework: If <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n \\n <mo>=</mo>\\n \\n <mrow>\\n <mo>{</mo>\\n \\n <mi>k</mi>\\n \\n <mo>}</mo>\\n </mrow>\\n </mrow>\\n </mrow>\\n </semantics></math>, then <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosability is equivalent to <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>k</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosability; if <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> consists of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>k</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> copies of 1, then <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosability is equivalent to <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>k</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourability. If <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> is <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosable, then <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>G</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> is <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mi>k</mi>\\n \\n <mi>λ</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourable. On the other hand, there are <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mi>k</mi>\\n \\n <mi>λ</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourable graphs that are not <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosable, provided that <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math> contains an integer larger than 1. Let <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>ϕ</mi>\\n \\n <mrow>\\n <mo>(</mo>\\n \\n <mi>λ</mi>\\n \\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n </mrow>\\n </semantics></math> be the minimum number of vertices in a <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <msub>\\n <mi>k</mi>\\n \\n <mi>λ</mi>\\n </msub>\\n </mrow>\\n </mrow>\\n </semantics></math>-colourable non-<span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>-choosable graph. This paper determines the value of <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>ϕ</mi>\\n \\n <mrow>\\n <mo>(</mo>\\n \\n <mi>λ</mi>\\n \\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n </mrow>\\n </semantics></math> for all <span></span><math>\\n <semantics>\\n <mrow>\\n \\n <mrow>\\n <mi>λ</mi>\\n </mrow>\\n </mrow>\\n </semantics></math>.</p>\\n </div>\",\"PeriodicalId\":16014,\"journal\":{\"name\":\"Journal of Graph Theory\",\"volume\":\"110 3\",\"pages\":\"283-289\"},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2025-06-15\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Graph Theory\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/jgt.23267\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Graph Theory","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/jgt.23267","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
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