The study of such graphs is called graph theory. Engineers need to find planarity in a graph when, for example, they are designing a computer chip without a crossed wire.

Here’s a good, clear post by Mark Chu-Carroll, a software engineer at Google, on graph theory. It describes how Euler used it to solve a conundrum involving bridges in Königsberg. In a previous ...

The graphs that mathematicians study can get very large and complicated, so it helps to have some simple features to look at. One such feature is the sum of all the degrees of a graph. Right away, ...

Abstractions blog Undergraduate Math Student Pushes Frontier of Graph Theory At 21, Ashwin Sah has produced a body of work that senior mathematicians say is nearly unprecedented for a college student.