about planarity

what is planarity

in graph theory a graph is a collection of vertices connected by edges. a graph is planar when it can be drawn on a flat plane without any edges crossing each other except at shared vertices.

planarity is the property that asks whether such a crossing free drawing exists. some graphs can be redrawn until the crossings disappear. others cannot be made planar at all.

read more on the wikipedia page for planarity.

what is a planarity puzzle

a planarity puzzle starts with a graph drawn with crossings. the vertices can move but the edges stay connected to the same vertices. the goal is to rearrange the graph until every crossing is gone.

that makes each puzzle a small search for a planar graph drawing. it is a graph puzzle game where the answer is not a number or word, but a drawing with the right edge crossings removed.

the original planarity game

the original planarity game was created by john tantalo. this site and game are inspired by the same graph puzzle idea.