Particular examples of dual graphs

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What is the dual graph (in the planar sense) of a totally disconnected graph on more than one vertex? I can't figure it out, considering that the graph is planar and the dual should be still well defined...

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The dual of a graph is defined as a dual vertex for each face and a dual edge for each edge, that connects the faces of each part of the edge.

Here you have one face (the outer face) so only one dual vertex, on no edge, so no dual edges. So your dual graph is the graph composed of one vertex and no edges.

You should remark that this dual graph is the same, no matter how many distinct vertices. This is not a problem because the classical results (each vertex gives one dual face, the dual of the dual of $G$ is $G$ itself) are only valid for connected graphs.