Packings, factors and factorizations of graph

I present three problems in graph theory: packings of graphs, factors of graphs and factorizations of graphs. This thesis contains the results of eight papers, six of them already published. Containing the results of four of the eight papers, Chapter 1 is devoted to the problems of packing two or three copies of a graph into a complete graph of the same order. Most of the results in Chapter 1 were obtained in cooperation with Norbert Sauer. I present a survey of packings of graphs followed by a general discussion. Chapter 2 is used to discuss the existence of certain factors of graphs, especially of bipartite graphs. I am interested in cycle factors and path factors of bipartite graphs which satisfy certain properties and will obtain some necessary and sufficient conditions for such factors to exist. Two main theorems are proved. Chapter 3 contains three main results about factorizations of a complete bipartite graph. Although a complete bipartite graph is seemingly simple, it turns out to factorize a complete bipartite graph into factors with given properties is not an easy task. The obvious numerical conditions obtained directly from the given properties are not sufficient to guarantee the existence of the factors satisfying the properties. Some specific technique should be developed further.;Each of these three chapters consists of introduction including some history, main results and discussion or remarks.