Domination number of the non-commuting graph of finite groups

oleh: Ebrahim Vatandoost, Masoumeh Khalili

Format: Article
Diterbitkan: Indonesian Combinatorial Society (InaCombS); Graph Theory and Applications (GTA) Research Centre; University of Newcastle, Australia; Institut Teknologi Bandung (ITB), Indonesia 2018-10-01

Deskripsi

<p>Let <span class="math"><em>G</em></span> be a non-abelian group. The <span><em>non-commuting graph</em></span> of group <span class="math"><em>G</em></span>, shown by <span class="math">Γ<sub><em>G</em></sub></span>, is a graph with the vertex set <span class="math"><em>G</em> \ <em>Z</em>(<em>G</em>)</span>, where <span class="math"><em>Z</em>(<em>G</em>)</span> is the center of group <span class="math"><em>G</em></span>. Also two distinct vertices of a and b are adjacent whenever <span class="math"><em>a</em><em>b</em> ≠ <em>b</em><em>a</em></span>. A set <span class="math"><em>S</em> ⊆ <em>V</em>(Γ)</span> of vertices in a graph <span class="math">Γ</span> is a <span><em>dominating set</em></span> if every vertex <span class="math"><em>v</em> ∈ <em>V</em>(Γ)</span> is an element of <span class="math"><em>S</em></span> or adjacent to an element of <span class="math"><em>S</em></span>. The <span><em>domination number</em></span> of a graph <span class="math">Γ</span> denoted by <span class="math"><em>γ</em>(Γ)</span>, is the minimum size of a dominating set of <span class="math">Γ</span>. &lt;/p&gt;&lt;p&gt;Here, we study some properties of the non-commuting graph of some finite groups. In this paper, we show that <span class="math">$\gamma(\Gamma_G)&amp;lt;\frac{|G|-|Z(G)|}{2}.$</span> Also we charactrize all of groups <span class="math"><em>G</em></span> of order <span class="math"><em>n</em></span> with <span class="math"><em>t</em> = ∣<em>Z</em>(<em>G</em>)∣</span>, in which <span class="math">$\gamma(\Gamma_{G})+\gamma(\overline{\Gamma}_{G})\in \{n-t+1,n-t,n-t-1,n-t-2\}.$</span></p>