 Dual graph

In graph theory, a dual graph is a construction that relates to a planar graph. To understand dual graphs, it's important to start with the concept of a planar graph itself. A planar graph is a graph that can be drawn on a plane without any edges crossing. ### Key Concepts of Dual Graphs 1. **Vertices of the Dual Graph**: For every face (region) in the original planar graph, there is a corresponding vertex in the dual graph.