The subchromatic number of a graph
Discrete Mathematics - Graph colouring and variations
Scheduling with incompatible jobs
Discrete Applied Mathematics
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Weighted Node Coloring: When Stable Sets Are Expensive
WG '02 Revised Papers from the 28th International Workshop on Graph-Theoretic Concepts in Computer Science
Computing
The complexity of satisfiability problems
STOC '78 Proceedings of the tenth annual ACM symposium on Theory of computing
Graph Subcolorings: Complexity and Algorithms
SIAM Journal on Discrete Mathematics
Graphs and Hypergraphs
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Starting from a batch scheduling problem, we consider a weighted subcoloring in a graph G; each node v, has a weight w(v); each color class S is a subset of nodes which generates a collection of node disjoint cliques. The weight w(S) is defined as max{w(K) = Σv ∈ K w(v)|K ∈ S}. In the scheduling problem, the completion time is given by Σi = 1k w(Si) where J = (S1,...., Sk) is a partition of the node set of graph G into color classes as defined above. Properties of such colorings concerning special classes of graphs (line graphs of cacti, block graphs) are stated; complexity and approximability results are presented. The associated decision problem is shown to be NP-complete for bipartite graphs with maximum degree at most 39 and triangle-free planar graphs with maximum degree k for any k ≥ 3. Polynomial algorithms are given for graphs with maximum degree two and for the forests with maximum degree k. An (exponential) algorithm based on a simple separation principle is sketched for graphs without triangles.