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Indicated total domination game

Michael A. Henning, Douglas F. Rall

Abstract

A vertex $u$ in a graph $G$ totally dominates a vertex $v$ if $u$ is adjacent to $v$ in $G$. A total dominating set of $G$ is a set $S$ of vertices of $G$ such that every vertex of $G$ is totally dominated by a vertex in $S$. The indicated total domination game is played on a graph $G$ by two players, Dominator and Staller, who take turns making a move. In each of his moves, Dominator indicates a vertex $v$ of the graph that has not been totally dominated in the previous moves, and Staller chooses (or selects) any vertex adjacent to $v$ that has not yet been played, and adds it to a set $D$ that is being built during the game. The game ends when every vertex is totally dominated, that is, when $D$ is a total dominating set of $G$. The goal of Dominator is to minimize the size of $D$, while Staller wants just the opposite. Providing that both players are playing optimally with respect to their goals, the size of the resulting set $D$ is the indicated total domination number of $G$, denoted by $γ_t^{\rm i}(G)$. In this paper we present several results on indicated total domination game. Among other results we prove that the indicated total domination number of a graph is bounded below by the well studied upper total domination number.

Indicated total domination game

Abstract

A vertex in a graph totally dominates a vertex if is adjacent to in . A total dominating set of is a set of vertices of such that every vertex of is totally dominated by a vertex in . The indicated total domination game is played on a graph by two players, Dominator and Staller, who take turns making a move. In each of his moves, Dominator indicates a vertex of the graph that has not been totally dominated in the previous moves, and Staller chooses (or selects) any vertex adjacent to that has not yet been played, and adds it to a set that is being built during the game. The game ends when every vertex is totally dominated, that is, when is a total dominating set of . The goal of Dominator is to minimize the size of , while Staller wants just the opposite. Providing that both players are playing optimally with respect to their goals, the size of the resulting set is the indicated total domination number of , denoted by . In this paper we present several results on indicated total domination game. Among other results we prove that the indicated total domination number of a graph is bounded below by the well studied upper total domination number.
Paper Structure (11 sections, 16 theorems, 1 equation, 7 figures)

This paper contains 11 sections, 16 theorems, 1 equation, 7 figures.

Key Result

Lemma 1

(CoDaHe-80) A TD-set $S$ in a graph $G$ is a minimal TD-set if and only if every vertex $v \in S$ has an open $S$-external private neighbor or an open $S$-internal private neighbor, that is, if and only if $|{\rm epn}(v,S)| \ge 1$ or $|{\rm ipn}(v,S)| \ge 1$.

Figures (7)

  • Figure 1: A graph $G$
  • Figure 2: The graph $G_k$ in the family $\mathcal{G}$
  • Figure 3: The graph $F_k = (K_k \,\square\, K_2) - u_kv_k$
  • Figure 4: The graphs $B_4$ and $J_4$
  • Figure 5: The tree $T_k$ in the proof of Proposition \ref{['prop:subdivide-star']}
  • ...and 2 more figures

Theorems & Definitions (18)

  • Lemma 1
  • Proposition 1
  • Proposition 2
  • Theorem 1
  • Proposition 3
  • Proposition 4
  • Proposition 5
  • Proposition 6
  • Theorem 2
  • Proposition 7
  • ...and 8 more