Graph bipartization and via minimization
SIAM Journal on Discrete Mathematics
On the k-coloring of intervals
Discrete Applied Mathematics
On perfectness of sums of graphs
Discrete Mathematics
The Approximation of Maximum Subgraph Problems
ICALP '93 Proceedings of the 20th International Colloquium on Automata, Languages and Programming
Polyhedral results for the bipartite induced subgraph problem
Discrete Applied Mathematics - Special issue: International symposium on combinatorial optimization CO'02
Packing and partitioning orbitopes
Mathematical Programming: Series A and B
IPCO '07 Proceedings of the 12th international conference on Integer Programming and Combinatorial Optimization
IPCO '07 Proceedings of the 12th international conference on Integer Programming and Combinatorial Optimization
Extended Formulations for Packing and Partitioning Orbitopes
Mathematics of Operations Research
Fundamental domains for integer programs with symmetries
COCOA'07 Proceedings of the 1st international conference on Combinatorial optimization and applications
IPCO'08 Proceedings of the 13th international conference on Integer programming and combinatorial optimization
Branch-cut-and-propagate for the maximum k-colorable subgraph problem with symmetry
CPAIOR'11 Proceedings of the 8th international conference on Integration of AI and OR techniques in constraint programming for combinatorial optimization problems
Symmetric ILP: Coloring and small integers
Discrete Optimization
A polyhedral approach for the equitable coloring problem
Discrete Applied Mathematics
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Given an undirected node-weighted graph and a positive integer k, the maximum k-colorable subgraph problem is to select a k-colorable induced subgraph of largest weight. The natural integer programming formulation for this problem exhibits a high degree of symmetry which arises by permuting the color classes. It is well known that such symmetry has negative effects on the performance of branch-and-cut algorithms. Orbitopes are a polyhedral way to handle such symmetry and were introduced in Kaibel and Pfetsch (2008) [2]. The main goal of this paper is to investigate the polyhedral consequences of combining problem-specific structure with orbitope structure. We first show that the LP-bound of the integer programming formulation mentioned above can only be slightly improved by adding a complete orbitope description. We therefore investigate several classes of facet-defining inequalities for the polytope obtained by taking the convex hull of feasible solutions for the maximum k-colorable subgraph problem that are contained in the orbitope. We study conditions under which facet-defining inequalities for the polytope associated with the maximum k-colorable subgraph problem and the orbitope remain facet-defining for the combined polytope or can be modified to yield facets. It turns out that the results depend on both the structure and the labeling of the underlying graph.