A planar graph is a graph (in the combinatorial sense) that can be embedded in a plane such that the edges only intersect at vertices. Consider tagging with [tag:combinatorics] and [tag:graph-theory].

A planar graph is a graph (in the combinatorial sense) that can be embedded in a plane such that the edges only intersect at vertices. Consider tagging with combinatorics and graph-theory.

A finite graph $G$ is planar if and only if no minor of $G$ is the complete graph $K_5$, or the complete bipartite graph $K_{3,3}$ (Wagner's Theorem).