Journal of Combinatorial Optimization

, Volume 35, Issue 4, pp 1009–1041

# Integer programming approach to static monopolies in graphs

• Babak Moazzez
• Hossein Soltani
Article

## Abstract

A subset M of vertices of a graph is called a static monopoly, if any vertex v outside M has at least $$\lceil \tfrac{1 }{2}\deg (v)\rceil$$ neighbors in M. The minimum static monopoly problem has been extensively studied in graph theoretical context. We study this problem from an integer programming point of view for the first time and give a linear formulation for it. We study the facial structure of the corresponding polytope, classify facet defining inequalities of the integer programming formulation and introduce some families of valid inequalities. We show that in the presence of a vertex cut or an edge cut in the graph, the problem can be solved more efficiently by adding some strong valid inequalities. An algorithm is given that solves the minimum monopoly problem in trees and cactus graphs in linear time. We test our methods by performing several experiments on randomly generated graphs. A software package is introduced that solves the minimum monopoly problem using open source integer linear programming solvers.

## Keywords

Static monopoly Integer programming Polytopes Valid inequalities Cactus graphs Majority thresholds

## Mathematics Subject Classification

05C69 05C85 90C10 90C57

## Notes

### Acknowledgements

The authors are thankful for insightful comments from the anonymous referee that helped to improve the presentation of the results.

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## Authors and Affiliations

1. 1.Department of MathematicsKennesaw State UniversityKennesawUSA
2. 2.Department of MathematicsUrmia University of TechnologyUrmiaIran