{"title":"将偏序分解成链","authors":"Kenneth P. Bogart","doi":"10.1016/S0021-9800(70)80059-X","DOIUrl":null,"url":null,"abstract":"<div><p>Dilworth's theorem gives the number of chains whose union is a given partially ordered set in terms of intrinsic properties of the partial ordering. This paper uses Dilworth's theorem to find the number of chains needed to uniquely determine a given partially ordered set in terms of intrinsic properties of the partial ordering. If <em>a</em> covers <em>b</em> and <em>c</em> covers <em>d</em>, then (<em>a, b</em>) and (<em>c, d</em>) are <em>incomparable covers</em> if either <em>a</em> or <em>b</em> is incomparable with either <em>c</em> or <em>d</em>. We prove that the number of chains whose transtitive closure is a given partial ordering is the largest number of elements in any set of incomparable covers plus the number of isolated elements of the partially ordered set.</p></div>","PeriodicalId":100765,"journal":{"name":"Journal of Combinatorial Theory","volume":"9 1","pages":"Pages 97-99"},"PeriodicalIF":0.0000,"publicationDate":"1970-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80059-X","citationCount":"3","resultStr":"{\"title\":\"Decomposing partial orderings into chains\",\"authors\":\"Kenneth P. Bogart\",\"doi\":\"10.1016/S0021-9800(70)80059-X\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Dilworth's theorem gives the number of chains whose union is a given partially ordered set in terms of intrinsic properties of the partial ordering. This paper uses Dilworth's theorem to find the number of chains needed to uniquely determine a given partially ordered set in terms of intrinsic properties of the partial ordering. If <em>a</em> covers <em>b</em> and <em>c</em> covers <em>d</em>, then (<em>a, b</em>) and (<em>c, d</em>) are <em>incomparable covers</em> if either <em>a</em> or <em>b</em> is incomparable with either <em>c</em> or <em>d</em>. We prove that the number of chains whose transtitive closure is a given partial ordering is the largest number of elements in any set of incomparable covers plus the number of isolated elements of the partially ordered set.</p></div>\",\"PeriodicalId\":100765,\"journal\":{\"name\":\"Journal of Combinatorial Theory\",\"volume\":\"9 1\",\"pages\":\"Pages 97-99\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1970-07-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/S0021-9800(70)80059-X\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Combinatorial Theory\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S002198007080059X\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Combinatorial Theory","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S002198007080059X","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Dilworth's theorem gives the number of chains whose union is a given partially ordered set in terms of intrinsic properties of the partial ordering. This paper uses Dilworth's theorem to find the number of chains needed to uniquely determine a given partially ordered set in terms of intrinsic properties of the partial ordering. If a covers b and c covers d, then (a, b) and (c, d) are incomparable covers if either a or b is incomparable with either c or d. We prove that the number of chains whose transtitive closure is a given partial ordering is the largest number of elements in any set of incomparable covers plus the number of isolated elements of the partially ordered set.