The
(p,k)-coloring problems generalize the usual coloring problem by replacing stable sets by cliques and stable sets.
Complexities of some variations of
(p,k)-coloring problems (split-coloring and cocoloring) are studied in line graphs; polynomial algorithms or proofs of NP-
completeness are given according to the
complexity status. We show that the most general
(p,k)-coloring problems are more difficult than the cocoloring and the split-coloring problems while there is no such relation between the last two problems. We also give
complexity results for the problem of finding a maximum
(p,k)-colorable subgraph in line graphs. Finally, upper bounds on the optimal values are derived in general graphs by sequential algorithms based on Welsh–Powell and
Matula orderings.