Map graphs
Zhi‐Zhong Chen, Michelangelo Grigni, Christos H. Papadimitriou · Journal of the ACM · 2002
We consider a modified notion of planarity, in which two nations of a map are considered adjacent when they share any point of their boundaries (not necessarily an edge , as planarity requires). Such adjacencies define a map graph . We give an NP characterization for such graphs, derive some consequences regarding sparsity and coloring, and survey some algorithmic results.