Partitioning Graphs into Induced Stars

Akira Saito1, Manoru Watanbe2
1 Department of Mathematics Nihon University Sakurajosui 3-25-40 Setagaya-ku, Tokyo 156 JAPAN
2Department of Applied Mathematics Okayama University of Science Ridai-cho 1-1 Okayama-shi, Okayama 700 JAPAN

Abstract

A partition \(\mathcal{D} = \{V_1, \ldots, V_m\}\) of the vertex set \(V(G)\) of a graph \(G\) is said to be a star decomposition if each \(V_i\) (\(1 \leq i \leq m\)) induces a star of order at least two.
In this note, we prove that a connected graph \(G\) has a star decomposition if and only if \(G\) has a block which is not a complete graph of odd order.