{"title":"The condition for a sequence to be potentially $A_{L, M}$- graphic","authors":"S. Pirzada, Bilal A. Chat","doi":"10.22108/TOC.2017.20361","DOIUrl":null,"url":null,"abstract":"The set of all non-increasing non-negative integer sequences $pi=(d_1, d_2,ldots,d_n)$ is denoted by $NS_n$. A sequence $piin NS_{n}$ is said to be graphic if it is the degree sequence of a simple graph $G$ on $n$ vertices, and such a graph $G$ is called a realization of $pi$. The set of all graphic sequences in $NS_{n}$ is denoted by $GS_{n}$. The complete product split graph on $L + M$ vertices is denoted by $overline{S}_{L, M}=K_{L} vee overline{K}_{M}$, where $K_{L}$ and $K_{M}$ are complete graphs respectively on $L = sumlimits_{i = 1}^{p}r_{i}$ and $M = sumlimits_{i = 1}^{p}s_{i}$ vertices with $r_{i}$ and $s_{i}$ being integers. Another split graph is denoted by $S_{L, M} = overline{S}_{r_{1}, s_{1}} veeoverline{S}_{r_{2}, s_{2}} vee cdots vee overline{S}_{r_{p}, s_{p}}= (K_{r_{1}} vee overline{K}_{s_{1}})vee (K_{r_{2}} vee overline{K}_{s_{2}})vee cdots vee (K_{r_{p}} vee overline{K}_{s_{p}})$. A sequence $pi=(d_{1}, d_{2},ldots,d_{n})$ is said to be potentially $S_{L, M}$-graphic (respectively $overline{S}_{L, M}$)-graphic if there is a realization $G$ of $pi$ containing $S_{L, M}$ (respectively $overline{S}_{L, M}$) as a subgraph. If $pi$ has a realization $G$ containing $S_{L, M}$ on those vertices having degrees $d_{1}, d_{2},ldots,d_{L+M}$, then $pi$ is potentially $A_{L, M}$-graphic. A non-increasing sequence of non-negative integers $pi = (d_{1}, d_{2},ldots,d_{n})$ is potentially $A_{L, M}$-graphic if and only if it is potentially $S_{L, M}$-graphic. In this paper, we obtain the sufficient condition for a graphic sequence to be potentially $A_{L, M}$-graphic and this result is a generalization of that given by J. H. Yin on split graphs.","PeriodicalId":43837,"journal":{"name":"Transactions on Combinatorics","volume":"6 1","pages":"21-27"},"PeriodicalIF":0.6000,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Transactions on Combinatorics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.22108/TOC.2017.20361","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
The set of all non-increasing non-negative integer sequences $pi=(d_1, d_2,ldots,d_n)$ is denoted by $NS_n$. A sequence $piin NS_{n}$ is said to be graphic if it is the degree sequence of a simple graph $G$ on $n$ vertices, and such a graph $G$ is called a realization of $pi$. The set of all graphic sequences in $NS_{n}$ is denoted by $GS_{n}$. The complete product split graph on $L + M$ vertices is denoted by $overline{S}_{L, M}=K_{L} vee overline{K}_{M}$, where $K_{L}$ and $K_{M}$ are complete graphs respectively on $L = sumlimits_{i = 1}^{p}r_{i}$ and $M = sumlimits_{i = 1}^{p}s_{i}$ vertices with $r_{i}$ and $s_{i}$ being integers. Another split graph is denoted by $S_{L, M} = overline{S}_{r_{1}, s_{1}} veeoverline{S}_{r_{2}, s_{2}} vee cdots vee overline{S}_{r_{p}, s_{p}}= (K_{r_{1}} vee overline{K}_{s_{1}})vee (K_{r_{2}} vee overline{K}_{s_{2}})vee cdots vee (K_{r_{p}} vee overline{K}_{s_{p}})$. A sequence $pi=(d_{1}, d_{2},ldots,d_{n})$ is said to be potentially $S_{L, M}$-graphic (respectively $overline{S}_{L, M}$)-graphic if there is a realization $G$ of $pi$ containing $S_{L, M}$ (respectively $overline{S}_{L, M}$) as a subgraph. If $pi$ has a realization $G$ containing $S_{L, M}$ on those vertices having degrees $d_{1}, d_{2},ldots,d_{L+M}$, then $pi$ is potentially $A_{L, M}$-graphic. A non-increasing sequence of non-negative integers $pi = (d_{1}, d_{2},ldots,d_{n})$ is potentially $A_{L, M}$-graphic if and only if it is potentially $S_{L, M}$-graphic. In this paper, we obtain the sufficient condition for a graphic sequence to be potentially $A_{L, M}$-graphic and this result is a generalization of that given by J. H. Yin on split graphs.