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Abstract The subject of this thesis is based on a field of mathematics called graph theory. In this branch we concentrated on Orthogonal Double Cover (ODC). The thesis consists of fourth chapters: Chapter one: Basic Concepts of Graph Theory It is an introduction for the following chapters and contains some of the main concepts of graph theory which will be used through out our work. Also it is illustrates complete bipartite graphs, complete graphs and orthogonal double cover (ODC) of each graph. Chapter two: The Construction Methods for Orthogonal Double Covers We construct ODCs of the complete bipartite graphs by using two half starters and specially by a symmetric starter method. In our work, we use the construction definition of orthogonal labeling of complete graphs. Chapter three: ODC of Complete Bipartite Graphs by Disjoint Union of Graphs In this chapter, we have proved that there are symmetric starter vectors on ODC of caterpillar with paths, caterpiller with stars and paths with cycles. Also, we have proved that there exist a symmetric starter vector of kite graph with modified kite graph and complete bipartite graphs. The existence of a symmetric starter vector on ODC of by , where , ( and ( ), and , where ( and is an even number, are given. Then, we have shown that the symmetric starter vectors of ODCs for some kinds of different disjoint union of paths are exist. Finally, the existance on ODC of the complete bipartite graphs are studied, by some certain disjoint union of paths. This is done by using a new idea of two half starter vectors, and show that there exists a half starter vectors of complete bipartite graph, by disjoint union of graphs. Some results in this chapter are accepted for publication in ARS Combinatoria Journal, and some of others accepted for presentation in International Conference for Mathematics and Applications (ICMA18) and another some accepted for presentation in International Conference on Mathematics, Statistics & Information Technology ( ICMSIT 2018). Chapter four: Cyclic Orthogonal Double Cover of Complete Graphs by Disjoint Union of Graphs In this chapter, we have shown that there exist CODCs of complete graph by disjoint union of graphs using orthogonal labelling method. |