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Decomposition of zero divisor graph into cycles and stars
⁎Corresponding author. ravisankar.j@vit.ac.in (J.Ravi Sankar)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of Ain Shams University.
Abstract
For a graph G and a subgraph H of G, an H-decomposition of G is a partition of the edge set of G into subsets , such that each induces a graph isomorphic to H. A graph is said to be non-zero zero divisor graph of commutative ring ℝ with identity if and if and only if . It is prove that complete decomposible into cycle of length 4 of an H-decomposition of the zero divisor graph where H is any simple connected graph. In particular, we give a complete solution to the problem in the case (n times). For any positive integer , there exists a decomposition of into cycle and stars in a commutative ring ℝ. We show that the obvious the graph is decomposition into cycle and stars. Overall, the proposed of the graph has significantly improved the decomposing to algebraic structure which can be useful for networking. In this paper we investigate the concept of is decomposition into cycles and stars as a commutative rings and with p is a prime number. It is prove that the zero divisor graph is complete decomposible into cycle of length 4 and star. In particular, we give a complete solution to the problem in the case ( times). For any positive integer , there exists a decomposition of into cycle and stars in a commutative ring . We show that the obvious the graph is decomposition into cycle and stars. Overall, the proposed of the graph has significantly improved the decomposing to algebraic structure which can be useful for networking area.
Keywords
Graph decomposition
Zero divisor graph
Balanced complete bipartite
05C25
06A11
05C70

1 Introduction
Throughout this paper, let us take only simple, finite, non-directed graphs. For further graph theory terminology in general, refer (Bondy and Murty, 1976). Let us consider the complete graph on vertices for the zero divisor graph as and also consider the complete bipartite graph on and vertices for the zero divisor graph . If R is the commutative ring and then the zero divisor graph is said to be balanced complete bipartite graph with vertices. Here represents the cycle with vertices and edges as . Also represents the star graph with a centre vertex and k end vertices as . The edges can be partitioned into such that subgraph induced by , where i lies between 1 and k. Let the graph is the decomposition of and we write . If , then is known as D-decomposition and it is denoted by where . If the zero divisor graph can be decomposed into a times of and b times of , then we can say as -decomposition or -multidecomposition. If this decomposition is true for every a and b with necessary conditions then has -decomposition or complete -decomposition (Shyu, 2010, 2012, 2013).
The multidecomposition was introduced by Abueida and Daven (2003) and they proved the existence of -multidecomposition of when , where n = 3,4 and 5 (Abueida and Daven, 2004, 2007, 2000). Priyadharsini and Muthusamy (2009) showed the necessary and sufficient conditions for when exists, where . Lee (2013) discussed the necessary and sufficient conditions for the multidecomposition of into minimum one copy of and . Also the necessary and sufficient conditions for the existence of decomposition of product graphs into paths and cycles with 4-edges is derived by Jeevadoss and Muthusamy (2016). Moreover Ilayaraja et.al, enterded their results for the decomposition of product of graphs into paths and stars on 5-vertices. Many other results on decomposition of zero divisor graphs into distinct subgraphs involving cycles, complete and stars have been proved in Alspach and Marshall (1994), Bryant and Maenhaut (2004) and Huang (2015).
The zero divisor graph concept was initiated by I.Beck in 1988 (Beck, 1998) and he considered zero for constructing zero divisor graphs. Few years later Anderson and Livingston, 1999 rearranged I.Beck’s definition by removing zero from his vertex set while constructing his graph. For further algebraic graph theory terminology in Kuppan and Ravi Sankar (2020)].
2 Decomposition of
If is a square graph, then the commutative ring .
The vertices are non-zero zero divisors. Therefore is
The graph is a balanced complete bipartite graph iff p is any prime and .
Suppose be the balanced complete bipartite graph, then the vertex set of . Now consider the vertex subsets as and . Let or with then no two vertices in or is non-adjacent. For any two vertices and such that we say that the edges from each vertex in to every vertices in . Hence . Conversely, consider the ring with vertex set is non-zero zero divisors . For all with and . Suppose there exists an edge from u to v. Clearly, the commutative ring is a graph of and it is a balanced complete bipartite graph.
Let p be any odd prime then the graph is decomposition into copies of .
The vertex set of such that lies between 1 and . That is . Let and be the partition of vertex subsets where and . That is and . Let any two vertices or then . Clearly u and v are disconnected.
Let us consider the any one member in and another member in then . Clearly u and v are connected.
Therefore, each vertex of is connected to every vertices in . That is is balanced complete bipartite graph in the form of .Clearly, can be decomposed into copies of . That is total values of each cycle is . Therefore, can be decomposed into copies of .
Let us consider and the vertex set of as
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Then can be split into two parts, namely and .
and.
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Clearly, is isomorphic to . The Figs. 1,2 indicates the decomposition of the graph into 25 copies of .
Let p be odd prime and are the non-negative integers. If there exists -decomposition of , then .
Let p be odd prime, the graph is -decomposable. Then
We shall prove this theorem by using the following two cases.
Case(i): Let . Assume that is divided by 4. Let us consider the vertex set of non-zero zero-divisors . Here be the zero divisor graph of a ring . If there is a member then such that the two zero divisors are non-adjacent. If there is a member and then, such that two zero divisors are adjacent. That is . Clearly, the graph completely decomposed star with size 4.Case(ii): Let . Assume that is not divided by 4. If there is a member then such that two zero divisors are non-adjacent. Clearly, the vertex is not completely decomposed into the star graph of size 4.
If a and b are any two positive integers, then there exists a complete -decomposition of .
Let . Then the required entire decomposition of are
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and . The required cycles are
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and . The required cycles and stars are
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and . The required stars are .
If a and b are any two positive integers, then there exists a complete -decomposition of .
Let . Then the required entire decomposition of are
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and the required cycles are
,
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and the required cycles and stars are
,
,
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and the required cycles and stars are
,
,
,
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and the required cycles and stars are
,
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,
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, .
Let a and b be any two positive integers and p is any prime number, then there exists a complete -decomposition of for all .
If , then the result follows by Lemmas 2.6 and 2.7. For , we write, where from 1 to . Let . By Lemma 2.6 and 2.7, the graphs have a complete -decomposition. Clearly, the graph has the desired decomposition.

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3 Decomposition of
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For any odd prime p then is decomposition into 3 copies of and 3 copies of .
Let be the zero divisor graph of a commutative ring . The vertex set where p is any odd prime. The vertex set can be partitioned into several disjoint subsets and . That is and .
Case(i): Consider the vertex subsets and . If with then the vertices are non-adjacent. If with then there is an edge between every pair of vertices. Clearly, the above subsets are adjacent to each other. By continuing the same process we can prove the same with and . Hence, 3 copies of .
Case(ii): Consider the vertex subsets and . If with then the vertices are non-adjacent. If with then there is an edge between every pair of vertices. Clearly, the above subsets are adjacent to each other. Continuing the same process we can prove the same with and . Hence, 3 copies of . Therefore, from the above two cases, indicate the graph is decomposition into 3 copies of and 3 copies of .
For any odd prime p, then is decomposed into copies of .
If p is an odd prime, then the vertices are non-zero zero divisors where . That is . Let us take the vertex subsets are and . That is and . Let us prove this by the following two cases.
Case(i): Let us take the pairs of vertex subsets and . Here . Similarly we say that and .
Case(ii): Let us take the vertex subsets are and . Then every pair of above vertex subsets are isomorphic to tri-partite graph of .
On the whole there are copies of . If we continue the same process we get copies for and . Clearly, from the above cases we get copies of . Therefore, can be decomposed into copies of .
Let p be any odd prime, then is decomposed into copies of and copies of .
Consider the vertex set of is . Let us consider the following subsets and are in .
Case(i): Let us take the vertex subsets and . Then every pair of subsets are isomorphic to . Cardinality of above all subsets is . If or or and then they are non adjacent to each other. If every distinct pair of vertices are connected then there exists a tripartite graph. If the size of the pair is then the decomposition of the graph yields copies. Similarly we can say that, if the sizes of and is then the decomposition of the graph has copies.Case(ii): Let us take the pairs of vertex subsets and . Then every pair of subsets are isomorphic to . Cardinality of above all pairs of subsets is . If and then they are non adjacent to each other. If the size of the pair is then the decomposition of the graph yields copies. Similarly we can say that, if the sizes of and is then the decomposition of the graph has copies. Clearly, from the above cases, we get copies of and copies of .
Let p be any odd prime, then can be decomposed into copies of copies of and copies of .
Let the vertex set of non-zero zero divisors is where . That is . The partition of vertex subsets are and . That is and . We can prove this proof by the following cases.
Case(i): Consider the vertex subsets and . If we decompose the tripartite graph then we get copies of and copies of . Which are written as follows.
If we remove copies of then the resultant graph will have and copies of edges only. Here the degree of each vertex is of even degree.
Case(ii): Consider the following vertex subsets and . That is . By Theorem 3.3 we say that copies of . Therefore, from the above two cases, we get is decomposition into copies of copies of and copies of .
4 Decomposition of
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If p is any odd prime, then is decomposed into 3-copies of , 4-copies of , 6-copies of and 12-copies of .
Let the vertex set is . The vertex set can be split into disjoint subsets, such as , where . That is and .
Case(i): Consider the vertex subsets and . If with then the vertices are non-adjacent. If with then there is an edge between every pairs of vertices. Clearly, the above subsets are adjacent to each other. Clearly, we get 4 copies of .
Case(ii): Consider the vertex subsets and . If with then the vertices are non-adjacent. If with then every pair of vertices are connected. Clearly, the above subsets are isomorphic to . Therefore, we get 4 copies of .
Case(iii): Consider the vertex subset of . If with then the vertices are adjacent. Clearly, every pair of is adjacent to itself. Therefore, we get 3 copies of .
Case(iv): Consider the vertex subset . If with then the vertices are adjacent. Clearly, the every pair of is adjacent to itself. Therefore, we get 6 copies of .
From the above four cases we say that is decomposed into 3-copies of , 4-copies of , 6-copies of and 12-copies of .
If p is any odd prime, then is decomposed into copies of and copies of .
The vertex set of . The vertex set can be split into disjoint subsets, such as , where . That is and .
Case(i): Let us consider the vertex subsets.
. If with then there is an edge between every pair of vertices. Clearly, we get 4 copies of complete graph .
Case(ii): Let us consider the pair of subsets and (using Theorem 4.1). The resultant of decomposition of is isomorphic to . Similarly the resultant of decomposition of and is isomorphic to and . Then we get cycles of length 4 and described as follows.
Sum of above decomposition .
Therefore, from the above two cases we get is decomposed into copies of and copies of .
5 Decomposition of
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If p is odd prime and m is any non-negative integer, then has partitions.
The vertex set of
The vertex set can be split into.
,
,
⋮
where (up to m times). That is , similarly .
Let the edge set Hence, the result.
It is obtained from the above results, we can find the following theorem.
For any odd prime p, then is complete decomposible into cycle of length 4.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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