Testing whether or not a graph is planar is an important aspect of graph theory. Wagner’s Theorem provides a characterization of planar graphs based on graph minors. 512 more words

## Tags » Planar Graphs

#### A few interesting open problems

- Does the class of constant-degree expanders have polynomially-long induced paths?
- Planar embedding conjecture — Can every planar graph equipped with an arbitrary shortest-path metric be embedded into L1 with only a constant distortion? 65 more words

#### Boron and Buckyballs

Recent news from the world of chemistry: the result is really the experimental observation of a special new molecule. People call it a “Boron Buckyball”, but this irritates me since we know that the buckyball is a specific fullerene on 60 vertices. 840 more words

#### Fellowship Interaction Graphs

In high school I had an argument with a friend after seeing a particular XKCD comic called Movie Narrative Charts. We were in math class at the time, an introductory calculus course if memory serves. 2,438 more words