TY - JOUR ID - Chen2007 LB - Chen2007 AU - Chen, Xue-gang TI - Tree domatic number in graphs ST - Tree domatic number in graphs JO - Opuscula Math. JA - Opuscula Math. JF - Opuscula Mathematica PY - 2007 VL - 27 IS - 1 SP - 5 EP - 11 DO - http://dx.doi.org/10.7494/OpMath.2007.27.1.5 UR - http://dx.doi.org/10.7494/OpMath.2007.27.1.5 AB - A dominating set \(S\) in a graph \(G\) is a tree dominating set of \(G\) if the subgraph induced by \(S\) is a tree. The tree domatic number of \(G\) is the maximum number of pairwise disjoint tree dominating sets in \(V(G)\). First, some exact values of and sharp bounds for the tree domatic number are given. Then, we establish a sharp lower bound for the number of edges in a connected graph of given order and given tree domatic number, and we characterize the extremal graphs. Finally, we show that a tree domatic number of a planar graph is at most \(4\) and give a characterization of planar graphs with the tree domatic number \(3\). KW - tree domatic number KW - regular graph KW - planar graph KW - Cartesian product SN - 1232-9274 ER -