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标题：L(3,2,1)- and L(4,3,2,1) -labeling problems on interval graphs
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作者：Sk Amanathulla ; Sk Amanathulla ; Madhumangal Pal 等
期刊名称：AKCE International Journal of Graphs and Combinatorics
印刷版ISSN：0972-8600
出版年度：2017
卷号：14
期号：3
页码：205-215
DOI：10.1016/j.akcej.2017.03.002
语种：English
出版社：Elsevier
摘要：For a given graph G = ( V , E ) , the L ( 3 , 2 , 1 ) - and L ( 4 , 3 , 2 , 1 ) -labeling problems assign the labels to the vertices of G . Let Z ∗ be the set of non-negative integers. An L ( 3 , 2 , 1 ) - and L ( 4 , 3 , 2 , 1 ) -labeling of a graph G is a function f : V → Z ∗ such that | f ( x ) − f ( y ) | ≥ k − d ( x , y ) , for k = 4 , 5 respectively, where d ( x , y ) represents the distance (minimum number of edges) between the vertices x and y , and 1 ≤ d ( x , y ) ≤ k − 1 . The L ( 3 , 2 , 1 ) - and L ( 4 , 3 , 2 , 1 ) -labeling numbers of a graph G , are denoted by λ 3 , 2 , 1 ( G ) and λ 4 , 3 , 2 , 1 ( G ) and they are the difference between highest and lowest labels used in L ( 3 , 2 , 1 ) - and L ( 4 , 3 , 2 , 1 ) -labeling respectively. In this paper, for an interval graph G , it is shown that λ 3 , 2 , 1 ( G ) ≤ 6 Δ − 3 and λ 4 , 3 , 2 , 1 ( G ) ≤ 10 Δ − 6 , where Δ represents the maximum degree of the vertices of G . Also, two algorithms are designed to label an interval graph by maintaining L ( 3 , 2 , 1 ) - and L ( 4 , 3 , 2 , 1 ) -labeling conditions. The time complexities of both the algorithms are O ( n Δ 2 ) , where n represent the number of vertices of G .
关键词：KeywordsenFrequency assignment L ( 3 , 2 , 1 ) -labeling L ( 4 , 3 , 2 , 1 ) -labelingInterval graphs