a b s t r a c tGiven a graph together with a partition of its vertex set, the minimum selective coloring problem consists of selecting one vertex per partition set such that the chromatic number of the subgraph induced by the selected vertices is minimum. The contribution of this paper is twofold. First, we investigate the complexity status of the minimum selective coloring problem in some specific graph classes motivated by some models described in . Second, we introduce a new problem that corresponds to the worst situation in the minimum selective coloring; the maximum selective coloring problem aims to select one vertex per partition set such that the chromatic number of the subgraph induced by the selected vertices is maximum. We motivate this problem by different models and give some first results concerning its complexity.Input: An undirected graph G = (V , E) and a clustering V = (V 1 , . . . , V p ) of V . Output: A selection V * such that χ (G[V * ]) is minimum. Let k ≥ 1 be a fixed integer.
k-Dsel-ColInput: An undirected graph G = (V , E) and a clustering V = (V 1 , . . . , V p ) of V . Question: Does there exist a selection V ′ such that χ (G[V ′ ]) ≤ k? We call such a selection a k-colorable selection. For any k ≥ 1, k-Dsel-Col is clearly in NP in general graphs and consequently we will not mention NP-membership in