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Paired-Domination Game Played in Graphs<sup>∗</sup>Haynes, Teresa W., Henning, Michael A. 01 June 2019 (has links)
In this paper, we continue the study of the domination game in graphs introduced by Brešar, Klavžar, and Rall [SIAM J. Discrete Math. 24 (2010) 979-991]. We study the paired-domination version of the domination game which adds a matching dimension to the game. This game is played on a graph G by two players, named Dominator and Pairer. They alternately take turns choosing vertices of G such that each vertex chosen by Dominator dominates at least one vertex not dominated by the vertices previously chosen, while each vertex chosen by Pairer is a vertex not previously chosen that is a neighbor of the vertex played by Dominator on his previous move. This process eventually produces a paired-dominating set of vertices of G; that is, a dominating set in G that induces a subgraph that contains a perfect matching. Dominator wishes to minimize the number of vertices chosen, while Pairer wishes to maximize it. The game paired-domination number γgpr(G) of G is the number of vertices chosen when Dominator starts the game and both players play optimally. Let G be a graph on n vertices with minimum degree at least 2. We show that γgpr(G) ≤ 45 n, and this bound is tight. Further we show that if G is (C4, C5)-free, then γgpr(G) ≤ 43 n, where a graph is (C4, C5)-free if it has no induced 4-cycle or 5-cycle. If G is 2-connected and bipartite or if G is 2-connected and the sum of every two adjacent vertices in G is at least 5, then we show that γgpr(G) ≤ 34 n.
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Jeux combinatoires dans les graphes / Combinatorial games on graphsRenault, Gabriel 29 November 2013 (has links)
Dans cette thèse, nous étudions les jeux combinatoires sousdifférentes contraintes. Un jeu combinatoire est un jeu à deux joueurs, sanshasard, avec information complète et fini acyclique. D’abord, nous regardonsles jeux impartiaux en version normale, en particulier les jeux VertexNimet Timber. Puis nous considérons les jeux partisans en version normale, oùnous prouvons des résultats sur les jeux Timbush, Toppling Dominoeset Col. Ensuite, nous examinons ces jeux en version misère, et étudionsles jeux misères modulo l’univers des jeux dicots et modulo l’univers desjeux dead-endings. Enfin, nous parlons du jeu de domination qui, s’il n’estpas combinatoire, peut être étudié en utilisant des outils de théorie des jeuxcombinatoires. / In this thesis, we study combinatorial games under differentconventions. A combinatorial game is a finite acyclic two-player game withcomplete information and no chance. First, we look at impartial gamesin normal play and in particular at the games VertexNim and Timber.Then, we consider partizan games in normal play, with results on the gamesTimbush, Toppling Dominoes and Col. Next, we look at all these gamesin misère play, and study misère games modulo the dicot universe and modulothe dead-ending universe. Finally, we talk about the domination game which,despite not being a combinatorial game, may be studied with combinatorialgames theory tools.
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Jeux de coloration de graphes / Graphs coloring gamesGuignard, Adrien 06 December 2011 (has links)
La thèse porte sur les deux thèmes des Jeux combinatoires et de la théorie des graphes. Elle est divisée en deux parties.1) Le jeu de Domination et ses variantes: Il s'agit d'un jeu combinatoire qui consiste à marquer les sommets d'un graphe de telle sorte qu'un sommet marqué n'ait aucun voisin marqué. Le joueur marquant le dernier sommet est déclaré gagnant. Le calcul des stratégies gagnantes étant NP-difficile pour un graphe quelconque, nous avons étudié des familles particulières de graphes comme les chemins, les scies ou les chenilles. Pour ces familles on peut savoir en temps polynomial si un graphe est perdant. Nous avons également étudié 28 variantes du jeu de domination, dont les 12 variantes définies par J. Conway sur un jeu combinatoire quelconque. 2) Le nombre chromatique ludique des arbres: Ce paramètre est calculé à partir d'un jeu de coloration où Alice et Bob colorient alternativement et proprement un sommet d'un graphe G avec l'une des k couleurs. L'objectif d'Alice est de colorier complètement le graphe alors que Bob doit l'en empêcher. Nous nous sommes intéressés au jeu avec 3 couleurs sur un arbre T. Nous souhaitons déterminer les arbres ayant un nombre chromatique ludique 3, soit ceux pour lesquels Alice a une stratégie gagnante avec 3 couleurs. Ce problème semblant difficile à résoudre sur les arbres, nous avons résolu des sous-familles: les 1-chenilles puis les chenilles sans trous. / Part 1: Domination Game and its variantsDomination game is a combinatorial game that consists in marking vertices of a graph so that a marked vertex has no marked neighbors. The first player unable to mark a vertex loses the game.Since the computing of winning strategies is an NP-hard problem for any graphs, we examine some specific families of graphs such as complete k-partite graphs, paths or saws. For these families, we establish the set of losing elements. For other families, such as caterpillars, we prove that exists a polynomial algorithm for the computation of outcome and winning strategies. No polynomial algorithm has been found to date for more general families, such as trees.We also study 28 variants of Domination game, including the 12 variants defined by J. Conway for any combinatorial game. Using game functions, we find the set of losing paths for 10 of these 12 variants. We also investigate 16 variants called diameter, for instance when rules require to play on the component that has the largest diameter.Part 2: The game chromatic number of treesThis parameter is computed from a coloring game: Alice and Bob alternatively color the vertices of a graph G, using one of the k colors in the color set. Alice has to achieve the coloring of the entire graph whereas Bob has to prevent this. Faigle and al. proved that the game chromatic number of a tree is at most 4. We undertake characterization of trees with a game chromatic number of 3. Since this problem seems difficult for general trees, we focus on sub-families: 1-caterpillars and caterpillars without holes.For these families we provide the characterization and also compute winning strategies for Alice and Bob. In order to do so, we are led to define a new notion, the bitype, that for a partially-colored graph G associates two letters indicating who has a winning strategy respectively on G and G with an isolated vertex. Bitypes allow us to demonstrate several properties, in particular to compute the game chromatic number of a graph from the bitypes of its connected components.
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