ARITHMETIC ODDDECOMPOSITION [AOD] OF SOMECLASS OF GRAPHS V.G. SMILIN SHALI Research Scholar, Reg. No. 12609, Research Department of Mathematics, Nesamony Memorial Christian College, Marthandam, Kanyakumari District, Tamil Nadu. Affiliated to ManonmaniamSundaranar University, Abishekapatti, Tirunelveli-627012, Tamil Nadu,India. S.ASHA Assistant Professor, Research Department of Mathematics, Nesamony Memorial Christian College, Marthandam, Kanyakumari District, Tamil Nadu. Affiliated to ManonmaniamSundaranar University, Abishekapatti, Tirunelveli-627012, Tamil Nadu,India. AbstractBy a graph , we mean a finite, undirected graph without loops or multiple edges. If 1 , 2 ,…, are connected edge- disjointsubgraphs of G with () = ( 1 )∪ ( 2 ) ∪ … ∪ ( ),then{ 1 , 2 ,…, } is said to be a decomposition of . The concept of arithmetic odd decomposition [AOD] was introduced by E. Ebin Raja Merly and N. Gnanadhas. A decomposition { 1 , 2 ,…, }of is said to be Arithmetic Decomposition [AD]if |( ) = + (- 1)d for every i = 1,2,..., anda,d Z + . An arithmetic odd decomposition [AOD] is an arithmetic decomposition with = 1 and = 2. We denote the AODby{ 1 , 3 ,…, 2−1 }. In this paper, we investigate AOD for some special class of graphs, namely , 1, ˄ 2 and ˄ 3 . Keywords:Decomposition of Graph, Arithmetic Decomposition, Arithmetic Odd Decomposition [AOD]. Introduction Let = ( , )be a simple connected graph with p vertices and q edges. If 1 , 2 ,…, are connected edge-disjoint subgraphs of G withE(G) = E( 1 ) ∪ E( 2 )∪ . .. ∪ E( ), then { 1 , 2 ,…, }is said to be a decomposition of G. Different types of decomposition of G have been studied in the literature by imposing suitable conditions on the subgraphs G i . The concept of Arithmetic Odd Decomposition [AOD] was introduced by E. Ebin Raja Merly and N. Gnanadhas. In this paper, we investigate AOD for some special class of graphs. Terms not defined here are used in the sense of Harary [3]. Preliminaries Definition 2.1. Let = ( , )be a simple graph of order p and size q. If 1 , 2 ,…, are edge- disjoint subgraphs of such that E(G) = E( 1 )∪ E( 2 ) ∪ . .. ∪ E( ), then { 1 , 2 ,…, }is said to be a decomposition of G. Definition 2.2. A decomposition 1 , 2 ,…, of a connected graph G is said to be a linear decomposition or arithmetic decomposition if each is connected and |( )| =  + ( − 1) , for 1≤≤ anda,d Z. Clearly = 2 [2 + ( − 1)]. Definition 2.3. When a = 1 and d = 1, the size of G is = (+1) 2 . When a = 1 and d = 2, the size of G is q = n 2 . Hence the number of edges of G is a perfect square. Since the number of edges of G is a perfect square, q is the sum of first n odd numbers 1, 3, 5, … , (2 − 1). Thus we call the arithmetic decomposition with a = 1 and d = 2 as Arithmetic Odd Decomposition (AOD). Since the number of edges of each subgraph of G is odd, we denote the International Journal of Applied Engineering Research ISSN 0973-4562 Volume 14, Number 8, 2019 (Special Issue) © Research India Publications. http://www.ripublication.com Page 63 of 67