Graphs and Digraphs - 1.) Give an example of a planar graph that contains no vertex of degree less than 5
2.) Show that every planar graph of order n≥4 has at least four vertices of degree less than or equal to 5. ...
Maximal planar graph - Prove that there exists only one 4-regular maximal planar graph.
Hint: there is a proof on two lines. If you don't find it, then it may take a page or two, but no more.
Planar Graph - Prove that the complete graph K5 is nonplanar.