Achromatic number is NP-complete for cographs and interval graphs
Information Processing Letters
The graph isomorphism problem: its structural complexity
The graph isomorphism problem: its structural complexity
The complexity of harmonious colouring for trees
Discrete Applied Mathematics - Special issue: Combinatorial Optimization 1992 (CO92)
Introduction to Algorithms
SODA '05 Proceedings of the sixteenth annual ACM-SIAM symposium on Discrete algorithms
Strong computational lower bounds via parameterized complexity
Journal of Computer and System Sciences
Parameterized Complexity
Hi-index | 5.23 |
We study the parameterized complexity of the pseudo-achromatic number problem: Given an undirected graph and a parameter k, determine if the graph can be partitioned into k groups such that every two groups are connected by at least one edge. This problem has been extensively studied in graph theory and combinatorial optimization. We show that the problem has a kernel of at most (k-2)(k+1) vertices that is constructable in time O(mn), where n and m are the number of vertices and edges, respectively, in the graph, and k is the parameter. This directly implies that the problem is fixed-parameter tractable. We also study generalizations of the problem and show that they are parameterized intractable.