Domination in transitive colorings of tournaments

An edge coloring of a tournament T with colors 1,2,…,k is called \it k-transitive \rm if the digraph T(i) defined by the edges of color i is transitively oriented for each 1≤i≤k. We explore a conjecture of the second author: For each positive integer k there exists a (least) p(k) such that every k-transitive tournament has a dominating set of at most p(k) vertices. We show how this conjecture relates to other conjectures and results. For example, it is a special case of a well-known conjecture of Erd\H os, Sands, Sauer and Woodrow (so the conjecture is interesting even if false). We show that the conjecture implies a stronger conjecture, a possible extension of a result of B\'ar\'any and Lehel on covering point sets by boxes. The principle used leads also to an upper bound O(22d−1dlogd) on the d-dimensional box-cover number that is better than all previous bounds, in a sense close to best possible. We also improve the best bound known in 3-dimensions from 314 to 64 and propose possible further improvements through finding the maximum domination number over parity tournaments

Domination problems in directed graphs and inducibility of nets

In this thesis we discuss two topics: domination parameters and inducibility. In the first chapter, we introduce basic concepts, definitions, and a brief history for both types of problems. We will first inspect domination parameters in graphs, particularly independent domination in regular graphs and we answer a question of Goddard and Henning. Additionally, we provide some constructions for graphs regular graphs of small degree to provide lower bounds on the independent domination ratio of these classes of graphs. In Chapter 3 we expand our exploration of independent domination into the realm of directed graphs. We will prove several results including providing a fastest known algorithm for determining existence of an independent dominating set in directed graphs with minimum in degree at least one and period not eqeual to one. We also construct a set of counterexamples to the analogue of Vizing\u27s Conjecture for this setting. In the fourth chapter, we pivot from independent domination to split domination in directed graphs, where we introduce the split domination sequence. We will determine that almost all possible split domination sequences are realizable by some graphs, and state several open questions that would be of interest to continue on this field. In the fifth chapter we will provide a brief introduction to Flag Algebras, then determine the unique maximizer of induced net graphs in graphs of certain orders