Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
MFCS '08 Proceedings of the 33rd international symposium on Mathematical Foundations of Computer Science
Introduction to Algorithms, Third Edition
Introduction to Algorithms, Third Edition
Martingales on trees and the empire chromatic number of random trees
FCT'09 Proceedings of the 17th international conference on Fundamentals of computation theory
Selective graph coloring in some special classes of graphs
ISCO'12 Proceedings of the Second international conference on Combinatorial Optimization
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We study the empire colouring problem (as defined by Percy Heawood in 1890) for maps containing empires formed by exactly r1 countries each. We prove that the problem can be solved in polynomial time using s colours on maps whose underlying adjacency graph has no induced subgraph of average degree larger than s/r. However, if s≥3, the problem is NP-hard for forests of paths of arbitrary lengths (if s